I never had a Fusion drive, either. But I notice that the article that Matti Haveri referred to says:
If you see a drive labeled Fusion Drive, your Fusion Drive is working and this article doesn't apply to you.
I clearly see the "Fusion Drive" label, so it doesn't seem like that is the problem. Why do you think that Photos is the cause of this? Unfortunately my Danish (and pretty much any non-English language--I'm an uncultured American, after all) is lacking, so I'm not sure what leads you to that.
The Disk Utility seems to say "Tilgængelig:" (Accessible) is 850 GB, is that right? and it also says 937 GB used, is that right? Used and Accessible add to 1.8TB! Sounds crazy. Mine looks like this:
with 828GB available, and 1.25 TB Used, which is close to 2 TB, which isn't so crazy.
You might try this article:
Use Apple Diagnostics to test your Mac - Apple Support
which does a hardware test of the Mac.
See what it says, and let us know what you figure out or what we can puzzle over…