He remembered the regulation from when he was here back in the 90’s, and then recently he stumbled upon this website below, which is basically a law firm. I’m not sure why he thinks the requirement has been brought back, based only on this website.
https://magnacarta.co.th/home/faq-section-2/thailand-tax-clearance-certificate/#:~:text=Thailand Tax Clearance Certificate is,compliant and of good standing