The Google translation refers to (A) "income due to work duties or business conducted abroad" or (B) "because of property".
A) Section 40 of the revenue code:
A1) Any of us is a tax resident of TH if we stay more than 180 days. Tax residency has nothing to do with the immigration status or the type of extension.
A2) "Income derived from employment, whether in the form of salary, wage, per diem, bonus, bounty, gratuity, pension, house rent allowance, monetary value of rent-free residence provided by an employer, ..."
"Pension" among all these types of income seems to refer to private pensions paid by an employer, (perhaps) not government pensions.
The double-tax treaty between your country and TH regulates where government pensions and private pensions are taxable. In previous years, many retirees could not even get a Thai Tax ID even when they asked for one.
B) Section 41 paragraph 2: capital gains, interest, dividends. "A resident of Thailand who in the previous tax year derived assessable income under Section 40 from an employment or from business carried on abroad or from a property situated abroad shall, upon bringing such assessable income into Thailand, pay tax."
This decree does not change the current tax law, which only imposes tax on financial income if you transfer it into TH in the same calendar year when it was earned.
Employment income is different - it's always taxable in TH if you earn it while you are in TH, even if you receive it from a foreign employer and park it in a foreign bank account.
(C) Income tax on capital, i.e. on the savings you transfer from your foreign savings account to TH: No, cannot happen. If you transfer 5mil THB of savings to buy a condo and TH were to impose 25% income tax on the incoming 5mil, then the real estate market would implode. This decree does not change the tax law, which only taxes income but not the substance or capital.
In the worst case, the revenue office may demand proof of how much financial income was included in the 5mil, e.g. 200,000 interest income in the months before it was transferred. Then they could impose a 5% tax on the 50,000 of interest that exceeds 150,000. That's not a new tax law. It was just not enforced.
(D) TH has signed up for the Automatic Exchange of Information with most other countries. So if an account owner is registered with a TH residence address with his bank in the EU, ANZ or UK, then the TH revenue department will receive data about incoming payments the next year. In 2025, a foreigner who received a 2024 stream of payments from some Western business in his Western bank account may be asked to explain the source: "We've got these data from your foreign bank. Did you earn foreign business or employment income while you lived (and apparently worked) in TH?"