yeah sounds like just the clearcoat.
Ive (stupidly) broken an ec70 before due to overtightening. When i first spotted what id done you could feel a ridge around the back of the post where the seatclamp had dug in, later you could see what looked like slight fraying of the fibers as the flex slowly snapped strand after strand. It finally went at kirroughtree, a bad landing off a jump and it felt like i was on my DH bike there was so much flex in the post 🙄 . We managed to pull it out the frame tho as it had still only split on the back half of the post, snapped the bottom bit off, shove it back in and i was good to go.