Yes no exit stamp when I go last November, I ask to the immigration lady if ok, she said to me it’s ok and when I re-enter by land 2 weeks later, no problem at all 👍
I don’t know where you live but in Pattaya they accept the affidavit from the French embassy only if this document is certified by the foreign affairs of Thailand (office in Pattaya central festival)
A same case in France some days ago, if you want a one year visa, you must ask for a 1 year covid insurance else you had only a 3 months visa according to the 3 months covid insurance