I managed to fix it by moving the game to a different drive. I've been struggling with this with a few other unity titles but only just made the connection a few minutes ago. Regedit and reboot didn't work for me personally. In terms of just unity games, some people have said moving them to your C: drive helps on Win11. However I have Win10 and moved mine to a third drive I have and it works fine now.Using the F95Zone search function in the thread reveals others have had similar problem with apparently no resolution. Not many, but a handful seem to have problems running Redux.
If you tried using a mod to do anything to the game, or your system just vomited a crash of the game... You could try - if you know how and take precautions not to brick your computer - you could go into your windows registry and delete your computer ever knowing it was there, and then retry after a reboot. May or may not work. Or, you could go in the developer's help channel on their discord and seek guidance. No one here has shared a remedy.
My steps were: regedit > removed UberPie folder > restart.
Then I moved my game files when regedit failed me.
GL, hope that helps some people.