Exchanging USDT/BUSD/UST for USDT/BUSD/UST

Assalamualaikum. Something has been bothering me for a few days. Is it permissible to exchange USDT/BUSD/UST for USDT/BUSD/UST? All of these tokens are pegged to US Dollar but have different native blockchain. Most of the time, when we exchange these currencies in between them, we don’t get it in 1:1 ratio. For example, If I want to exchange 1 USDT for BUSD, I will get 0.9996 BUSD and this value changes. So would it be permissible to exchange these stablecoins for another stablecoin? Thank you.