@Marvin ********
Dividends (or any other money) from 2023 and before are now your savings that are not assessable income for Thai income tax purposes. From 1.1.2024 onwards, foreign-source dividends you earn while a Thailand tax resident will not become tax-free savings but will be taxed if and when remitted to Thailand.
I believe tax credits will only be available during the year you receive the income, so to be able to deduct German tax you paid in 2024, you might have to remit the money in 2024. But this entire credit system for individuals has not been announced yet.