Photos app stuck on "Restoring from iCloud" since a week.

I've bought a brand-new MacBook Air (Apple M1 chip with 8‑core CPU, 8‑core GPU, and 16‑core Neural Engine, 1TB SSD). It performs well overall, but the photos app is really a shame.

I do have a 1GB fiberglas connection, but now I'm already waiting since a week that my photos library gets rid of this very annoying and useless "Restoring from iCloud" message.

You cannot even see the progress, except for the progress bar which is also stuck at around 98%.

Yes, I do have many photos and videos (more than 100k) but if Macs are not made for this then dont sell them as power machines. 

New photos that I take with my iPhone do not appear on the Macbook Air as long as the sync is ongoing. So I cannot work with the Macbook easily, means I have to copy my work manually to the laptop.

BTW I've tested to import a few older photos (and even videos) into the photos app on the Macbook, which actually worked and they got even synced to my iPhone. I think this is super-strange. 

The synchronization of old stuff works, while the latest photos do not appear.

This is just ridiculous.