“Starting January 1st, 2024, a Thai tax resident who brings foreign-earned income into Thailand must pay Thailand income tax.”
For me, it is very clear that they're asking for tax on the money you bring into Thailand. That means if you have 500.000 income and you bring only 250.000 into Thailand then they count from 250.000 and not from 500.000
If you have tax in your home country on your income and there is an agreement you can look at what the possibilities are, normally you pay only a one-time tax on your income. I have read your text however, the individual interpretation of certain segments might differ from person to person. Such as bringing in money periodically into Thailand as income (pension)or on the total amount of pension money.
Sorry for my Englisch but I try to my best