I am having the same issue on every game I play that supports the default bubble chat. You could fix this yourself by opening the BubbleChat localscript and modifying the textlabel’s size.
Edit: Someone has already posted a message about this in the Engine Bugs section, hopefully this bug can get fixed soon: Bubble Chat on mobile (and desktop?) cuts off
Edit 2: Looks like Roblox has acknowledged and getting this bug sorted! 