USD to GBP conversions through trading app - will I lose money through conversions

I am currently using an investments broker app to make trades/investments in to the stock market and crypto currencies. The broker app deals in USD currency which is converted from GBP when I deposit. When I close trades and withdraw funds I will need to convert it back from USD to GBP to enter my account.

On the assumption that the the USD will become ever weaker due to current inflation concerns, is this something which I should be worried about? My current portfolio contains Crypto Currency and Stock Market investments in the Chinese economy, but I am worried that having to withdraw in USD and then convert over to GBP will cause a loss for me in itself. Or would I be better off finding a broker app which deals exclusively with GBP, or does it make any difference at all?

This is all very new to me, and I am unsure about the affects of this. Thanks in advance.