Are there any Covid restrictions or vaccination proof required to leave and re-enter Thailand now?

There's no way one could be forced to show proof of vaccination to leave a country. That's a violation of human rights and as a foreigner you have the right to leave a country and go back to your own, without being required or compelled to undergo a medical procedure.

To enter a foreign country as a foreign national is a different story, there is no automatic right for non-citizens to enter.

Anyway, the whole Covid charade is over, except for a couple of countries in the region and central/southern Asia, including Indonesia, Myanmar, Philippines, Turkmenistan and Pakistan as well as a couple of Pacific Island nations.

Your wife's friend smoke to much weed been zero restrictions for months now

No more covid based requirements for Thailand. The only place that still has any are a couple of the land borders with Myanmar.