I seem to recall other threads were this was discussed with a very definitive solution.
Maybe mod related but I can't find that so possibly just corrupted save (character and/or world) because crash / shutdown / no time for steam to sync.
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How To Restore Most Recent Working World Save After Crash
Common Issues and Possible Solutions
(official help/FAQ/pinned post)

The general recommendation is to disable cloud saves completely but it's working fine for some.