In 1.14+ while flying when you try to crouch the crouching animation isn't applied to your character like it used to.
I'm assuming this is a bug because I can't imagine that being changed or removed.
Linked issues
duplicates 1
Comments 2
Thank you for your report!
We're actually already tracking this issue in MC-148428, so I resolved and linked this ticket as a duplicate.
However, that ticket has already been resolved. Depending on the resolution, that can mean that it either will be fixed in the next version, or that it is not considered a bug and won't be fixed.
If you haven't already, you might like to make use of the search feature in the future to see if the issue has already been reported.
Do you mean crouch flying? That probably got removed. This is a game with lots of issues open (at the time that I'm writing this) though, so it being a bug is more likely.