Bug when checking account (/api/v3/account) balances not consistent

Hi,
when i check the balances via /api/v3/account for my generated testnet account and open a trade it is not consistent.

Yesterday i bought ADA (ADAUSDT) for 3956.500000 as my quantity. When i checked today the balances, i noticed that only 3664.10000000 were left. What happened to the 292.4000000000001 ? I also noticed that i received addional usdt .

Could it be possible that this is a bug ?

regards,