We strongly advise using the respective ISA provider transferring service instead of withdrawing the funds yourself to add them to another ISA. This applies both if you transfer from or to Trading 212.
If you withdraw funds from one ISA to contribute to another, the money will count towards your ISA allowance. On the other hand, using the transfer service will ensure your funds remain in the ISA wrapper and your ISA allowance won't be affected. 👌