Recently some malicious users started to use an exploit where they would post rule violating content and then delete the account. This would prevent admins and mods from viewing the user profile to find other posts, and would also prevent federation of ban actions.
The new release fixes these problems. Thanks to @flamingos-cant for contributing to solve this.
Lemmy just released 0.19.14, which addresses this somehow, but the announcement is vague:
https://join-lemmy.org/news/2025-12-08_-_Lemmy_Release_0.19.14
https://discuss.online/post/31855056