Weird, maybe it's something else specific to my setup? But other Minecraft versions work just fine ...
I don't think this is an issue specific to Linux.
To recreate what i got, try pressing sprint, right and forward at exactly the same time. It might need a few attempts to get the timing right.
Yes
I'm experiencing similar, but less severe behavior (no freezes or keyboard changes) in the latest snapshot 18w01a: Mouse movement seems to have changed, to the point where I feel like I can't move properly anymore. This is especially noticeable in fast-paced PVP situations.
Interestingly enough i'm unable to reproduce this issue after switching keyboards ... possibly higher keyboard sample rate?