But there is a lot of missing info that makes it hard to even begin.As other's noted, it could be any number of things, some more common than others.It might not even be bathroom related, i.e. a roof leak that is showing itself in a bathroom (but presumably this would be present when raining and shortly thereafter).Toilet, could be wax ring or the O ring that connects tank to bowl.  

Most will likely stick to the technical limit of Sept 2021 when it ceased being a primary residence, but some may be comfortable going by the address on the 2021 return and others may explore a partial exclusion, depending on the reasons for your move abroad.If you'd like to read up on the technical rules, the IRS publication 523 gets into more detail than most people would like to know, but it does have some helpful tables and examples for different scenarios.

I love hearing insight from hosts who have solved this common pain point.

Feel free to message me and I can through you through each scenario, but your attorney is going to be your best resource when it comes to liability. 

Later, he took common asked qustions from the book tours and wrote another book.

Based on your current scenario you would need to qualify to be able to get a HELOC on your home.

The rest, set aside contingency funds to account for things you think may have been missed, unless its a terrible deal, move on.If the owner doesn't keep Quick books or any other accounting, you won't see a P&L or cash flow statement, so you'll be working off the leases.This is pretty common.  

Be sure you have verified their identity prior to sharing any sensitive information.Here’s the IRS article for further information.Have you had any of these scenarios happen to you?

Two questions: Do you think the scenario sounds right, or is there anything else to pay attention to?

IMHO it is literally the easiest way for “the common person” to build immense wealth.