I have a pig farm where they fall through a layer of lava and die on the floor below. I tried it today and the pigs didn't fall through and instead died in the lava.
With all the changes being made, it would not be overly surprising if the rate at which mobs fell through lava had also been changed… if you had the time-in-lava set to just perfectly kill by fall damage without cooking (or something similarly finely tuned) any change might be keepingthem in the lava blade too long.
Rollback Post to RevisionRollBack
WARNING: I have an extemely "grindy" playstyle; YMMV — if this doesn't seem fun to you, mine what you can from it & bin the rest.
Mobs die faster in 1.14.1 lava. My guardian farm used a 4 block deep lava blade to weaken the guardians, but now they die just before dropping out of the lava. I reduced it to 3 block depth and it seems to be working, although they still die faster than before