GENTLEMEN.

I've discovered the reason for this bug.

Yet again, Desync.

This occurs on this condition: If you fish on a tide waters where it retreats the moment you successfully pull out a fish, and technically it is temporarily ''unfishable'' / uninteractable from waters, since at the moment there is no water there, it retreated back due to the tide retreating.
The game decides to softlock the character, requiring to jump and reset the catch, aka time wasted and hook not spent with bait still remaining.

Fishing in 100% reliable waters that will still be in the correct distance you tossed the hook into, will not result in the desync, since the game upon pulling out the catch, will detect proper water and not just ground.

So main issue is the retreating waters, or fishing on the close waters on a river / sea. (while the prompt to fish appears, it may be deceiving and unreliable).
You always must aim the fishing throw of the rod, deeper into the waters, if you go too shallow, this bug occurs.

Can be reliably reproduced in a retreating tide / shallow waters.
Most reliable time to reproduce is during sunset, and sunrise, as the tide changes and temporarily allows the fishing prompt for a few seconds as it comes close, using that specific prompt and not aiming for deep waters, will cause the desync bug. wasted attempt wasted time.