Sorry to state the obvious but did you provide legal proof of the right to reside in the country you applied from? Either a residence permit, driving licence, national ID card or passport for that country. They only accept legal residents / citizens of Greece, Malta and Serbia. It used to be so easy. I didn't realise how lucky we were to have had a Thai Consulate in Malta. We used to just drop off our passports and pick them up with the 60 day visa sticker a few days later.
My husband did the tourist visa through Athens evisa last month. It was issued in less than 48 hours but we anticipated every possible query and sent extra information. For example the accommodation was in my name instead of his so we put a note on the hotel voucher to explain that we would travel together. His bank statement was old (only issued once a year) so we also sent a more recent download of transactions. You can only upload a single file so sometimes you need to merge pages into a pdf. I would phone them if I were you.
The problem is the requirement has only been sent to airlines, it has not been sent to consulates or embassies so there is not the usual guidance. The UK foreign office website still says there are NO restrictions on entering Thailand. I don't think this rubbish will last long. Emirates have not updated their website. It is still saying no restrictions for Thailand. This is what Qantas are saying on their website ''Travel from 9 January 2023
All passengers entering Thailand must provide evidence of being fully vaccinated according to Government of the Kingdom of Thailand guidelines.
This means having completed a full course at least 14 days before your day of travel. Your vaccination certificate must show your full name as per your passport and be written in English.''
The Thai guidelines are what I sent you and were also published on the Thai civil aviation website. I would just print them off and keep them to hand. In the absence of anything else they should stand.