Did you read the OECD link I posted ?
https://www.oecd.org/en/about/news/press-releases/2024/10/oecd-kicks-off-accession-process-with-thailand.html
Especially this paragraph
That is PC speak for, if you wish to join the OECD. You will implement what we tell you.
And the current tax regime in Thailand, where some 12 million file a tax return, some 4 million actually pay tax. Is never in a month of Sundays going to pass the OECD sniff test on best practice for the avoidance and evasion of tax.
Therefore, as long as Thailand continues with the current OECD accession path, changes to the tax system will be coming.