Problem when trying to place double slab on build limit

When trying to add slab to another slab on y level 255 the game show double slab for a moment(on servers) and after it regret and show that 255 is the build limit.

I spotted this bug on 1.15.2 but I suspects that this bug is the for longer time.

p.s. it actually pretty useful when you are trying to build a platform of bottom slab.