This is the latest official info from The Thai Revenue Department.
This is a new interpretation of the current tax laws The laws have not been changed (yet). This new interpretation makes assessable income taxable regardless of the year it was earned.
https://www.hlbthai.com/wp-content/uploads/2023/09/RD-Instruction-No.-Paw161-2566-Translation.pdf
The link is a 3rd party website but the document is the official Revenue Department Instruction dated 15 Sep 2023