Commonsense is chasing you but you need to slow down so it can catch up. New Immigraation rules would need to be enqacted by the Thai Parliament and pubished in the Government Gazette. There are no new Immigration rules. The rules have not changed, but the old (current) rules are being ienforced in a different way.
Everything that you state is fully correct. But what you do not state is that the changes ar not related to new rules but are changes to how the old rules are being interpreted.
I think that you run too fast for commonsense to catch you. These are not new rules. The rules have not changed only how the old rules are being interpreted.
I doubt very much that you came on a visa on arrival. I suspect that you came on a Visa Exempt Stamp which is not any kind of a visa. Thai Immigration is currently allowing 1 x 60 day visa exempt entry plus a 30 day extension and then one more 60 day visa exempt entry plus a 7 day extension. But to be on the safe side, in your shoes, next time I would apply for a visa appropriate to my reason for stay.