The unit was crappy to begin with and this didn't happen over a short period of time.

Overall, it is okay, but it still requires relinking the accounts periodically, which seems more security-related than anything else.

Flippers always get frustrated waiting for the home occupant period to end on them.

If they pass that initial trial period, I offer a 6-12 month renewal. 

Now it going above pre-pandemic was because like Miami, Nashville, and Boise, Austin was a super-fast grower and had massive companies relocate there during that period therefore homebuilders jumped on it.

I do have a nightly pet fee but i put in my listing that if someone is bringing a pet for an extended period of time they can also reach out to me to discuss a flat pet rate for their stay.

Tenants in arrears due to “loss of income related to COVID-19” have a six-month grace period—without late fees!

If so, I would definitely consider a shorter-term lease or MTM lease to get you into that period and re-negotiate with the current resident or re-lease it at a higher rate. 

Lawn you can get feelers during the due diligence period so that's not the end of the world.

If they paid Dec rent, then they still owe you for part of Jan (if the lease requires 30 days' notice-if more time is required, then they owe you rent for that period (unless you rent it).