And, to offer something positive too: I like Photoprism, it's very fast, browsing old photos just works with no extra delay, there's search by date, location, tags, even face detection.

Legit have had none of these issues.
I do get a notification once in a while if I modify a picture fast enough, like a quick crop and it's still uploading. Like snap pic and edit within the same 5 seconds or so.
Basically just a: "there are multiple versions of the same file (which is true), which one do you wanna keep".

Then again mine is running on a pretty beefy server which might hide issues rooted in performance.
I remember it being hell when I was running it on a RPi.

And you don't have your notification bar on the phone full of upload errors?

I get a bunch of upload errors for photos that I delete or move before nextcloud has a chance to upload them, those are safe to ignore. Not sure which errors you're getting...

Can you get to older photos in under an hour, while Nextcloud slowly loads one thumbnail per second?

Forget about the plain nextcloud photos app, use the Memories app (incl. the android app).

Not as good as immich, from what I understand, but if you already have nextcloud, or need more than just photos, it works well.

It is really unbeleviable how there are some people for whom Nextcloud just works, and the rest of us.

It's definitely not perfect, but since I was able to set it up to work well for me, I'm keeping it, at least until I have time to install immich and figure out how to sync the two (and maybe get a more powerful server to use its ML features). I'm currently running it off of a decade old chromebox ...