Maps should start in one sides favour, and dynamically change based on gens being completed.
A good example of this is the game map. Killer sided in that it's a small Locked off map (easy to patrol, terror radius effects more of it), where there are select paths to loop until doors are opened and pallets become more easily accessible as more paths to them are opened. However I think we should have maps be more.. dynamic in their changes even if there basic. It doesn't become completely survivor sided, but those doors certainly help with routing on occasion.
As a pure example of something that could be added - the corn maps which are rather survivor sided, create the symptom of corn blindness, making it hard to find survivors at the start of the match. What if as gens were done, the corn wilted and fell to the ground dead. Revealing large open spaces where survivors find it more difficult to hide. Ie the map becoming easier on killers as survivors progress their objective.
Other changes that could be made are things such as having naturally foggier maps (Ormond would fit this asthetic immensely.) Which then have the fog lift more and more as the generators "light up the map", hell this could even be added as a base feature of the game allowing for the fog add-ons to be more significant.
Other more survivor styled options (though I'm not suggesting this is added I'm using it as an example) in the boiler room of the game map, there is a very high ledge which survivors can leap down which usually leads to a pallet and killers can have a hard time following expecially when the survivor has balanced landing. Instead there could be a small gate powered by the generator that is usually next to it, that once powered will open the staircase allowing the player to drop down. - the same principle even could be used on haddonfields windows, being locked until they are later opened by generators powering the area.
There could also be map "mirages of the fog" things that are there that disapear and appear conditionally based on a killer/survivors influence over the area (ie gens done, hooked survivors etc) which could lead to loops or objects appearing and disapearing making the entity's realm feel even more incoherent and ever changing.
Tldr: having maps dynamically change based on the current power of killer or survivors allowing the game to equal out in favour of the other side if one side is winning.