Letting Killers leave during EGC
EGC can be the slowest, most immersion-breaking, and least tense part of a match, with survivors waiting in the gates and pushing the timer down to milliseconds for one reason or another; usually to annoy the killer, but this also annoys their spectating teammates who want them to simply leave so they can see the killer's build or talk to them in the pgc.
I propose that after some time in the EGC, maybe around 50% through, the killer has the option to leave/surrender the match in the basement (through holding M1 or some other interaction to prevent accidentally leaving.) This way the killer can't immediately leave and possibly annoy survivors who need challenges like getting out of the match last, but the killer doesn't have the "just leave!" problem of having to check both exit gates and flush out rats when they just want to move on to the next match.
Obviously if the killer leaves, any living survivors (including hooked/downed ones) immediately escape.
I think this would help phase out EGC toxicity, since killers wouldn't be forced to either engage with toxic survivors and reward them or stand in a corner and wait out the entire EGC, while still allowing survivors enough time to get to the gates and gain last minute healing points or do whatever they need to do. And if they still want to go and taunt the killer while they wait to be able to leave, they'll have to go to the basement to do it, which I think few killers would be opposed to.
(I also just like the idea of the basement being what connects the killer realms due to it consistently being present, so while the exit gates go to the survivors' campfire, the 'basement gate' brings the killer back to their home realm. For style points, maybe the killer's endscreen could reflect this, having them standing in the basement or walking through a tunnel/darker realm or something, rather than the same place survivors are, which seems a bit odd the longer I think about it.)