Howdy! It seems that when a slime is killed by salt, it turns into a magma cube, but this is listed nowhere on the wiki. Is this some other mod causing this behavior, or is this intentional? I couldn't find anything about it on the wiki...

Slimes turning into Magma Cubes when killed by magma is a new-ish Quark feature added in 1.19.2.

i didn't see anything like that

salt deals HOT_FLOOR damage, maybe you have a mod that adds some logic to slimes where they get converted when they die due to certain damage types?