Sending over USD 10K (or equivalent) has been an automatic flag for decades (yep, not inflation-adjusted).
Of course, it's for our own good and is definitely not a way to keep tabs on innocent transactions. But I digress.
If you were to try to send multiple amounts less than or equal to USD 9999, that is spotted too and is known as "layering", which might attract more attention.
It seems the Thai banking system's guidelines make people look criminals on occasion, doesn't it?