Prior to the 1.14.3 update, the amount of mouse acceleration when playing the game has been almost non-existent. But when i logged on just a few hours ago i could instantly tell something was wrong. The mouse acceleration had been turned up greatly which made my playing experience a lot less enjoyable.
I tried logging on the 1.14.2 update, and there everything was as usual. I then got back on the 1.14.3 update and the problem was still there.
There's nowhere in the settings that says anything about mouse acceleration neither in the 1.14.2 nor the 1.14.3 update.
I'm not sure if there's something wrong on my end but it sure is strange and really annoying.
Possibly caused by the recent update of lwjgl explained in this comment.