Rats no longer make rat holes.
Rats no longer pass under fences/gates.
Rats no longer bypass doors.
Rats no longer take any action properly when tamed unless put in a rat sack then put back down, to restart them, Or you restart the server/world.
Rat miners will go and dig a single block then just sit there.

.....These really need to be fixed, The issues are piling up the longer and longer they are left un-fixed, and need to be fixed so we have these features working properly again.

Fixed in 5e55839