The IRS discusses this in publication 504.
https://www.irs.gov/forms-pubs/about-publication-504
Basically, as far as the IRS is concerned, your ex can deduct property taxes for the period of time they were a legal owner of the home, but only if they actually paid the taxes. If you are the only person who paid property taxes in 2024, only you can deduct them. If your ex shared the house payments until May, your ex can deduct the portion of property taxes and mortgage interest that they actually paid.
If your ex has not shared the bills but is supposed to, that is something for your attorney.
