...I've noticed those types property here, are located in really bad areas, - wonder if other cities are different in this regard.Raf

Assuming the tenants are on leases, you will have to wait until the leases expire, and I typically give a lot of notice that I will not be renewing.  

If you're living in the property, rent is decreased or non-existent, affecting the property's ability to generate income.RESPA rules are real and have a purpose. 

Generally speaking, holding rents lower will decrease turn over.

I noticed he had a rental listed online that indicated that “their maintenance team” will be available to the renters.

In your case, you delivered notice to vacate.

It only appreciates or decreases in value a percentage of the change in my neighborhood median income from the time I bought, 2012, to the time I sold... yeah my situation is crazy!!!

Housing authority said I need to give an usual 20 day notice to vacate but are there any other laws (pandemic related or otherwise) I need to keep in mind?

Mid May I gave one of my tenants notice to vacate July 1.

Aug 17 posted 30 day notice to quit, squatter says he's actively looking for new placeAug 23, 2021 local power company posted 3 day notice to pull meter (or bring in contract, which squatter does not have)Aug 23 was last day we saw squatter living at cabin (we can see from our living room windows)Aug 26 power company pulled meterAug 27 CPS agent comes and documents living conditions Aug 27 posted a 7 day notice to evict due to hazard/danger/health conditionsAug 30 squatter and former tenant (she was in jail since Nov 2020 and this was her first time back on the property) stop by for 10 min, leave with an armful of paperwork, leave behind 4 flea bombs (the house is FULL of food waste and dirty clothes).