How about an Opt out option?

What if for survivors they could opt out of one killer and killers could opt out of one map? Besides everyone having a much more enjoyable time preventing the thing that could ruin their time the most, it could provide valuable information for devs to see which maps killers don't enjoy and which killers survivors choose to avoid. Also nice since killers don't have to worry about getting certain maps that are just completely unbearable for their power (eg: Billy doesn't have to worry about being sent to Lery's) or troll maps that are extremely survivor sided (Racoon Police Department) and survivors don't have to worry about getting the same killer 4/5 matches for the time they can play (Wraith or Spirit) or maybe a killer they struggle with for specific reasons (Ghost face is near impossible for me to spot a lot of the time since I'm colorblind)

Possible issues

That means SWF's would get to pick 4 killers they veto. For SWFs I would say the party leader should only get to choose the killer vetoed. If you're playing with friends it's assumed you're in comms and that's enough of an upper hand given to you.

What happens if a survivor wants to put in a map offering for a map the killer vetoes? Just simply make it unable to be chosen as an offering similar to how things like the moonlight bouquets are.

It will be impossible for some killers to get matches! There's always the possibility, but there's 25 killers now. Everyone hates each different killer for their own different reason. Some cause they're super sweaty, some cause they're far too frequent, some cause they're too meta, some cause they're played unfun, some cause they're campy, etc. Yes obviously some killers will have higher veto rates than others and it's likely some of the more meta ones will be vetoed more than others but I doubt any one killer will have enough of the community use their singular vote on one killer enough to make a sizeable impact to queue times. And if it does there's probably a reason for that and should be addressed by the devs. If 80% of the survivor community band together to block one killer, do you really blame the community or do you think maybe there's a bigger issue at hand. Same exact thing when it comes to maps.

Would a killer veto Macmillain Estate or only be able to block suffocation pit? I would say since it's potentially 4 survivors vetoing 4 killers and they're all happy, why not let the killer veto an entire category of maps? Plus this veto feature is for the benefit of the player, as someone who's color blind I can not maintain a chase on coldwind to save my life due to losing the scratch marks in the corn. Blocking coldwind as a whole would be nice to get that entire factor out of the rotation as opposed to just the Thompson house.

Are you really claiming there's no issues with this feature? No but there's almost no features in video games that don't come with a downside and I think this one has far more ups than downs. The only issue I can think of that I can't find a real answer for is that with this feature, that means a lobby of 4 solo queue players could effectively veto 4 different killers and that could honestly make queue times longer, but tunny enough it would be longer for survivors than it could for killers lol. But I seldom am part of a lobby with 3 other solo queue players myself so this could potentially be a non issue? Not sure but the only real glaring issue I see with this feature. Plus the icing on the cake is you don't even have to choose veto out of anything if you don't want to.