Can I return to Thailand on a visa exempt 60-day stay in 2025 after my previous stays and extensions?

If in doubt, buy a visa in your country before you leave. It's inexpensive and easy.

get a tourist visa before you leave

Ultimately it is still legal and ultimately it’s up to the immigration officer dealing with your passport. And as long as I’ve been living here, over a decade, that’s the way it’s always been. Now that they have the DTV immigration may well be getting more stringent I. Order to sell more DTVs. But who knows…

If you get the 60 day visa exempt stamp and extend by a further 30 days at the Immigration office, Immigration class you as a tourist. If you then attempt to enter again on a visa exempt stamp, Immigration rightly consider that after on 90 day stay in the country that you are no longer a tourist but that you are attempting to live long term in the country. While there is no legal limit to the number of Visa exempt entries, once the Immigration officer believes that you are no longer visiting the country as a tourist he will deny you entry. 3. If you have already stayed for 90 days on a visa exempt entry, then in future to guarantee entry into Thailand, you need to obtain a long term visa suitable to the reason for your stay.

On the face of it you only came twice last year using visa exempt, you've also been away for 5 months, really not an issue for entering again IMHO. But of course you may encounter an IO having a bad day. Have the three proofs as mentioned if you are concerned.

As mentioned, it's up to the IO at the airport but as you have been away for 5 months, it's fairly clear that you are not trying to live here on visa exempt and extension stamps so you should be ok provided you have the 3 requirements when you arrive, if asked for them.

A new year makes zero difference. It will be up to the Immigration officer you will stand in front of to make that decision

Only the IO that you face can tell you that. Make sure you have the big 3 when you come, onward travel, 20k cash and confirmed accommodation, that is all you can do. Or buy a tourist visa before you come.