Some context... sorry this is long but there might be a solution below...
So I started to get this too. I have almost 200 hours across mp and sp. Ran great on Very High. However, in the last couple of weeks I progressively got more and more d3d_device_context errors. And today it decides to do this big red box after the videos that you described. It's as if it slowly corrupted itself into a corner.
I've tried more than enough troubleshooting for the d3d errors with driver and game re installs, messing with game and GPU settings, underclocking, and other various suggestions so going this backwards was pretty demoralizing.
Potential solution though...
One thing I'm seeing now though is that deleting/removing the file (compressed_shader_cache.sack) from this folder (C:\Program Files (x86)\Steam\steamapps\common\Mount & Blade II Bannerlord\Shaders\D3D11) stops the red square issue from occurring for me.
I've played with removing and re adding that file as suggested in another thread in an attempt to troubleshoot the d3d errors without any noticeable change but I think the red square started happening today after I re added it at some point or after a total reinstall of the game.
So BlitZBaK, try removing that file from that folder and then start the game. It seems to have worked for me even though it wasn't a problem in the past. I still get the d3d errors but I'm at least past the startup sequence now and continue troubleshooting those.
Also, I have an entirely different GPU (Nvidia) than BlitZBaK and havent touched mods so far, and the game has run mostly fine on Very High for 190+ hours, so I don't think this is related to those things specifically but who knows.
GTX 1070 8GB, 16GB RAM, i7-6700k 4GHz, bannerlord version e1.4.0.229571
I hope this is useful, good luck.