Investors & landlords

I had 4 rental properties in the past. I managed them myself.  One year, in order to meet the safe harbor criteria, I HONESTLY recorded all the activies I spent on the rental management (including contractors'). The total hours were way below 250 hours, thus I gave up my attempt to use safe harbor since then, and I never claimed QBI deduction on my rental property income including this year ( I know some similar landlords did even they didn't meet safe harbor criteria) as I think it might cause IRS audit because I am a part-time landlord and my rental management activity is considered to be passive, additionally, Section 162 defining a rental business is vaguer.   I just don't know how IRS figured out this 250 hours threshold , at least it never applied to my case.