The emphasis is on assessable income. The recent Revenue Department Order No. 161/2566 is about income earned abroad, ie outside Thailand, that is assessable in Thailand.
If there is a Double Taxation Agreement (DTA) between Thailand and another country and if this DTA states that some income in that other country is assessable in that country, then that income is not assessable in Thailand. That's the purpose of a DTA, and it works both ways.
For the record, here is an English translation of the entire text of the Revenue Department Order No. 161/2566
Revenue Department Order 161-2566.pdf
And here is a link to the original Thai text of the Order, included in the news article linked to in the OP of this topic:
https://www.thaienquirer.com/wp-content/uploads/2023/09/IMG_3943.jpg