Breakable walls
Breakable walls have been the first new universal mechanic introduced into the game in years, and now that they've been in the game for more than a year themselves and are present on a variety of maps, I think there has been enough time for the team to oversee their impact, review their performance, and consider improvements.
It's great that you brought a new universal game mechanic at all, but I feel like breakable walls in their current state leave things to be desired. First of all, survivors cannot interact with breakable walls whatsoever, so they yield no real new gameplay for survivors as a mechanic - survivors can play around the possibility that the killer might break a wall in a chase, and they can attempt to blind or sneak past the killer while they're breaking it, but those are not new gameplay interactions unique to breakable walls, that's basically just a limited form of pallet gameplay. For killers on the other hand, breakable walls depending on their placement are much of the time either merely walls because they have no incentive to ever break them as they limit the survivors' possiblities without hampering their own (such as the ones closing off the upper-level rooms in Glenvale's saloon), or they are just sort of a chore because killers are basically obligated to break them in order to turn a strong structure more into their favour (e. g. the ones in the main buildings of Coal Tower and Groaning Storehouse). There are only a rare few exceptions of breakable walls that actually provide the killer with a more calculated decision to be made that has upsides and downsides, by opening up worthwhile pathways for both them and their opponents (the breakable walls on Gas Heaven come to mind).
I think an easy way to make breakable walls a more interesting and engaging mechanic would be to allow both killers and survivors to destroy them, but have them respawn in place automatically after a certain time (around 60 seconds). Survivors would "crash" through them, falling down and having to recover before they are able to continue running. The specifics of how long that animation lasts would be something to be experimented with, but somewhere around 2 seconds seems like it would allow for this to be done during chases albeit at a notable cost of having the killer close distance. The break animation for killers on the other hand should be sped up, to around 1-1.5 seconds. Breakable walls should favour killers more, with the current breaking time they are basically like pallets killers have to break. Plus with breakable walls respawning, obviously killers would not benefit nearly as much from breaking them outside of chases. With the shorter breaking time, killers would actually be able to get the jump on a survivor (in as well as outside of chases), allowing them to gain an immediate advantage out of it that can quickly result in a hit. And as we know from some of the special abilities that can break these walls, it's also a lot more fun to do so quickly or unexpectedly, "exploding" through them much to a survivor's surprise. And in the worst case where the survivor anticipates the break, the killer is at least losing less distance this way.
That's pretty much it. The walls would become a gameplay element that is much more interactive in chases and can be to the detriment and benefit of both sides. And with both killers and survivors able to break through these walls, immediately all of their existing placements become much more interesting because both sides have to make decisions when and whether at all to break through them (e. g. is it worth it for a survivor to spend 20 seconds opening up the side rooms in the saloon on the chance of someone getting chased around there within the next minute? Is it worth it to break through a wall to have a faster path to your next objective at the risk that your opponent might benefit from that opened pathway in the next 60 seconds?).