Confirmed for snapshot 19w03b.
I believe this is what they were talking about: https://youtu.be/3TerLFYRuU0
I included versions 1.7.10 and 1.12 in this video but I think the bug affects versions 1.9 and up.
Confirmed cape drifting in 1.11.
https://youtu.be/xdlOMHqo2vc here's a video of it in 1.11.
If you pull ou the screen where you type then hit the home button on your device then reopen minecraft the keyboard comes up and works. Mojang is currently work on this issue at the moment and will release an update to fix this bug.
I believe this bug started in version 1.8.