Clicking sound coming from rear In the middle of one ride my bike started making clicking sound from the rear.
And I can't find the source since that.

Here is a video of it:
https://photos.app.goo.gl/RZKb7C3L76TbnMVF7

As many times suggested on this website, I tried adjusting L, H, B screws as well as cable tension and it didn't help. The sound is most noticeable on the lowest cog, but somewhat present on all.

Bike is one month old and it is built on Shimano 105 R7000. Chain is KMC X11EL.

Any advice please?

P.S. when separated, neither hub nor chain make any sound

UPD: I took the bike to the shop. After some time they said that the problem is with the hub and they fixed it. However they didn't give me the details about the fix.
After I came home - I found that nothing is fixed and the sound is still there. It just wasn't noticeable in shop's ambient noises
If you have a one month old bike bought new you should be able to take it to the shop you bought it from for a free drivetrain and brake tune up, and to address problems like these that crop up in the first few weeks of ownership.

The click is very loud and occurring at low speed. It does not sound like the indexing being off a little. It sounds like the chain in catching on something  but I cannot see it moving on the smallest sprocket so it's not trying to jump to the next largest sprocket.

I'd look to see if the chain in catching on something around the derailleur cage. 

Check that the wheel is seated in the dropouts properly. If the wheel shifted significantly the sprockets will not be parallel to the derailleur cage. Another possibility is that the derailleur hanger has been bent which will also misalign the sprockets and derailleur cage.