Hi Ck. I'm Greg, 10 years awarded Windows MVP, here to help you.
I've not yet heard of Focus Session bothering anyone. But I do notice that for some reason I'm not signed into the Clock app even though I'm signed into Windows with my MS Account.
Perhaps if you sign out of that one app at the top of the settings it will back off. There shouldn't be any reason to sign into the Clock except to enable it to access your data for the Focus sessions which you do not want.