Indeed, the confusing thing about this whole situation is that the rule seems now reversed to the opposite of what it was before.
Before you had to wait for the next year to bring in your earnings to Thailand to avoid it being taxed; now you will have to bring it in immediately to avoid it being taxed.
I agree with another user that in practice, it takes some doing to prove which money is earned in which year. Personally, I have savings, investments and bank accounts, and any money earned is mixed with other money earned previously in either of those places, and some of that money is sent ... well if I were actually able to open a bank account in Thailand, some of that money would be sent to Thailand. Since I am not, it finds other ways to Thailand, like cash, or send it to my girlfriend through Wise, after which she gives me cash.