notepad-plus-plus VS czkawka

No, actually Notepad++ has a dark mode, moreover you can install any theme, for example I like Dracula

https://github.com/qarmin/czkawka by far the best of anything iv tried

I've used Czkawka (https://github.com/qarmin/czkawka) because it does Lanczos-based image duplicate detection, which makes it more practical for me.

Maybe it's a setting you made or the files, not sure. You can try another software czkawka to see if you get better results with it.

For static images i used https://github.com/qarmin/czkawka and it works well enough. I think. But when i used it on a folder with gifs and their jxl conversions, it shows nothing. SURELY this could not be user error, rrrright?

I used to use DupeGuru which has some photo-specific dupe detection where you can fuzzy match image dupes based on content: https://dupeguru.voltaicideas.net/

But I switched over to czkawka, which has a better interface for comparing files, and seems to be a bit faster: https://github.com/qarmin/czkawka

Unfortunately, neither of these are integrated into Photoprism, so you still have to do some file management outside the database before importing.

I also haven't used Photoprism extensively yet (I think it's running on one of my boxes, but I haven't gotten around to setting it up), but I did find that it wasn't really built for file-based libraries. It's a little more heavyweight, but my research shows that Nextcloud Memories might be a better choice for me (it's not the first-party Nextcloud photos app, but another one put together by the community): https://apps.nextcloud.com/apps/memories

Czkawka can do this.

There's always the well-respected tool, Czkawka. Or, of the CLI is your thing, jdupes is a good option.