When using /player shadow to automate afk fishing i had one die and when re-connected with real client the player still had all exp and kept logout location. Should have been dead and forced to re-spawn

That was the most sensible way to handle death of fake players that don't have clients to handle the respawn screen. This can be revised now in 1.15 thanks to immediate respawn mechanics. Didn't look into it yet - that's something that definitely makes sense now.