@Martin ****
I know exactly what's going on. There was a minor reinterpretation in tax law (Paw 161/2566)
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) https://www.rd.go.th/fileadmin/user_upload/kormor/newlaw/dn161A.pdf
It's a minor change. Many people, especially retires were likely already responsible to pay tax under the law in previous years.
As most people in the groups come from counties that have tax treaties with Thailand, those apply the same.
I did pull up the neatherlands treaty, it's actually the most unique one I have seen. As a quick glance it doesn't have a competing residency clause.