It comes weird streaks, in the beginning I thought that someone hacked so I figured
nothing but I believe there is a bug because it comes on animals and other things too. Please fix it because it's very annoying.
MC-98234
The problem is that the lines are very wrong.
Resolved
Invalid
0
Those are the "hitboxes", one of the debugging options.
You can turn them on and off by pressing F3 together with the "B" key.
Could it be that you accidentally enabled them?