[TF2] Prediction errors causing issues with crouching, taunting, and general movement on Casual

[JoriKos]

Semi-related to #6080, except this is not on a listen server and not under certain conditions, but constantly and on Casual servers. I recall this issue happening once before and both times it was on Mercenary Park. This issue makes me completely unable to use the taunt menu, but I can force a taunt using the taunt cvar. Every time I crouched, my view moved up before moving to the correct position. It also caused a lot of stuttering on stairs.

I tried to reconnect to the server, which didn't fix the issue. I tried to restart my game, which did not work either. As I mentioned, this seems to only happen on Mercenary Park.

I've recorded 2 videos of it happening (ignore me missing shots that was on purpose trust me): https://youtu.be/OSRs5Es_soE

https://youtu.be/XT1rfLDkvt0

[NO-LOAFING]

I've run into this bug a number of times in Casual. It seems like movement prediction just stops working for the whole server until the map changes, causing all the jittery movement problems in the OP and stopping you from taunting (unless you're standing on a dynamic prop like a control point, which fixes the bug entirely?) I've had it happen on all sorts of maps - cp_junction, pl_corruption, and cp_steel, and I saw someone who had it on koth_king (looks like their video was taken down, though)

Interestingly, every time I've encountered the bug, you could hear physics scraping sounds in the background coming from nothing in particular, like a prop or ragdoll was scraping against the floor somewhere. I don't know what the connection is, but it's a pretty easy way to tell that the bug is happening.

Here's a collection of clips I took of the bug on junction: https://www.youtube.com/watch?v=GN8Dl903kns And a few more on other maps, uploaded as part of big messy clip dumps: https://www.youtube.com/watch?v=OYG0zS5rJ7Y (from 0:00 to 1:23) https://www.youtube.com/watch?v=JJ-xuWwzJms&t=43s (from 0:43 to 1:07)