BHVR, why not just have conditions for cheating?

The Speed one would be really hard to do.

Speed Modifiers Stack.

Breakout, Hope, Boon: Dark Theory, Adrenaline, Lithe, Smash hit, Balanced Landing, Sprint Burst, Blood Pact, Guardian, and Clowns Piss bottle

A lot of these can make a speed way faster than 4.0.

especially if combined

So the Speed cap would have to account for these

Then there is teleporting

they don't walk or run at all.

and rubber banding may or may not trigger it as well.

Speed hacking detection would have to be more complicated than that.

It is perfectly feasible that, for example, a survivor can be moving faster than 4.0m/s for longer than a minute, because Hope exists and lasts for 2 minutes.

Not saying it's a bad idea, but it wouldn't be as simple as "are they moving faster than their default speed for x length of time."

As good as an idea this would be... you're expecting too much from a company that built this game on spaghetti code.

It'd be easy to build a net that captures blatant cheating (the kind where survivors hook and unhook themselves 15 times per second and fly around the map spamming animations, or the killer is a flying Ghostface with machine gun hatchets), but subtle cheating is much harder to catch because it falls within the parameters of what can already happen normally in DBD. You'd need to run an extensive list of if/elseifs every second to make sure that player speed matches perks and powers, buffs and cooldowns are lasting as long as they should and no more or less, and that nobody is affected by perks that aren't supposed to be in play, and that kind of overhead would slow down the game - not necessarily a great idea when it's already so strapped for performance.

It'd be much simpler if you could run a check to make sure all the values and conditions look okay only when an effect activates, but cheaters can alter the base values as well as inappropriately apply buffs to themselves, and that necessitates the costly constant checks. That said, they really should enforce that timers and cooldowns have very specific possible values and can never fall outside default/addon configurations, because that one should be way easier to detect without having to constantly spam checks - if the killer is stunned for a minute after a Head On, or the survivor's Jigsaw box takes 10 minutes to search, someone is cheating and that should be visible to the system immediately.

If it was that easy, why hasn't it been done? Do all the sanity checks you want but it's still not this magic bullet.

Riot's Anti cheat was designed with the game from the ground up, and certain decisions were made when making the game that help make cheating harder. You can read the posts they have made regarding the implementation of a fog of war system and the issues they encountered doing so.

With VAC it scans only for cheats reported by the developer, and even then, still has issues with cheaters.

They need to change the Haste modifiers and make a monitor that validates the sources. All it needs to do is check the equipped perks, verify that perks in use are only 4, then ensure that marked "Shared" perks that grant movements speed to allies (Guardian, Dark Theory, etc.) have a shared, associated effect that doesn't stack. By making it that Haste does NOT stack, but favors the highest source, it would also make validating sources simple. If someone doesn't have Sprint Burst, but they are given 50% Haste sourced from Sprint Burst, Hacker. If they are moving 15% faster sourced from Guardian, Hacker. It would take a little doing, but it's 100% doable, especially with validated times. If a survivor enjoys over 50% movement speed for longer than 5 seconds, Hacker. If the Haste status exceeds all sources in the game, Hacker. If movement is higher than the base amount with an unverified source, Hacker.

Making Teleportation for killers marked for specifics isn't too hard, it could be done with a simple If/Then loop.

If: Killer using ability | Then: Ignore speed limitation . . . If: Killer uses ability at unreasonable frequency | Then: Flag for hacker.

So, if a survivor stays exhausted for 4 minutes, the game detects a hack and aborts? Not quite that easy, actually. There are several timers depending on action or inaction, and those could still be messed with.

Why cancel game just kick him of game

Yes and no. If a survivor recovers from exhaustion in two seconds, the game can detect a hack easy. Four minutes - as you say, it's possible they were running or working on gens with Fearmonger or whatever. But in the latter case, it's not about looking at how long the effect takes to expire, it's about looking at how quickly the timer decays when it's not paused.

I would expect that there's a numeric timer that shows how long the effect is supposed to last, as well as charges and the rate of charges per second that survivors progress when actively working on them. Both of these things should be able to detect when the expected value isn't lining up with any possible outcome (say a survivor is healing at 0.01 charges per second, or doing gens at 20 charges per second, or any value that exceeds any possible combo of perks and addons.)

While that's true, you don't have to nuke a match for discovering something wrong. The way I'd do it, having the server discover an irregularity would flag the match for BHVR to look at and record some data about the discovered anomaly (whether it's for the bug team or the team that handles reports and suspicious activity, it's useful to have this directly sent to them) and would allow players to disconnect from the match without any penalty. That way, people can play if they want to or if everything seems aboveground, but if someone's cheating, nobody is forced to play with them for the sake of their DC timeouts.

To this date, i had more killer hackers than survivors, just saying. However, since i mostly play survivor, i dont have perfect knowledge of what is going on, and only can identify hackers that do it obviously (like running faster than me the whole time, or instahealing) AND do it in front of me, while a hacking killer usually becomes an issue in every game, sooner or later. So that is not representative.

I havent personally encountered a killer hacker but this is not a "us vs them" or surv vs killer issue.

This issue is really hurting the game, both sides. Neither side should want cheaters to this magnitude.

I personally have encountered (with video proof) things like endless sabo survivors who can sabo hook in 1 second and has no cooldown can run to next hook before you get there and sabo that one too, had it done to me on video. Won't link my vid but its on YT, I can only mention what I have encountered, have not had killer bot yet.