In addition to that, the rental property itself was never reported as an asset either.
This is not as simple as just amending returns. Especially since you're talking more than 2 years back. What you have will be referred to as a "change of accounting method" which requires you to file IRS Form 3115 to fix this. While that form is included in the program, it's not simple by any stretch. Especially for you since you expensed items that you "may" have been required to be depreciated.
You need to seek professional help ASAP to get this fixed so the 3115 can be correctly filed with your 2021 tax return, everything corrected from the past, and bring it all up to date so that you can continue on your own next year.
Unless you yourself are well versed, I don't recommend tackling the 3115 yourself. Doing that wrong will just make things even worse. Overall, the expense of professional help will be cheaper than if you do the 3115 wrong.
