First thing is that, I am taking immuno-suppressing drug regularly.
Second thing is what is happening to me is (depending how you look at it) minor. I don't get cold symptoms anymore either (although I my first covid was just runny nose). The primary thing is that I get that mentioned tiredness. I think most people would chalk it up under having a bad day / not sleeping enough etc.
The thing though is that when it happens it comes with few other symptoms that I had when I had covid:
flare up, causing joint pain especially in the morning
first day there's a light diarrhea (also nothing concerning on its own, and following day is normal)
And those three things always come together at the same time.