In everygame I love infected mode, but a couple things to improve:

1- instead 1 round..more in the row..or loading, ending, and loading lobby and game again is more longer then game itself xD I suggest just 4 (or 5 rounds..) even more I'm happy -> I think that this is a must ?
2- let use the weapon someone prefer, attachments and buy gadjet! Maybe different for this mode.. (with more rounds even better as always with money! Or survivor from past rounds , if any, even good for them, of course if point 1 is done) -> think about it, for me it's cool
3- add lootbox with hp restore /syringe / ammo..etc maybe passive skill like speed and so on.. (and hey some money for buy if points 2 is done) -> great thing ^^
4- increase base speed for human, not to be faster then zombie but almost to run faster enough to hide better and faster.. -> this is a life quality improvements
5- decrease time gas granade remains, too bad for visibility -> less quitrag