"I had a self-only HDHP in all 2024"
I read this as indicating that the last-month rule was not used in 2024, so I'm not sure why there is any question about the last-month rule. Perhaps the answer provided to 2025 TurboTax's confusing question regarding 2024 HDHP coverage resulting in TurboTax behaving as if the last-month rule was used in 2024 when it was not. One can avoid 2025 TurboTax acting as if the last-moth rule was used in 2024 by answering None when asked about the type of coverage in 2024.
