Hi @atagunbugra , welcome to MetaMask community
Can you check on bsc scan if you can still see USDT balance or check on debank about your portfolio.
If you see balance as mentioned above in block-explorer, follow this article https://support.metamask.io/hc/en-us/articles/360028059272-What-to-do-when-your-balance-of-tokens-is-incorrect
If you don’t see any unauthorized transaction and still missing out USDT balance in block explorer , then contact pancakeswap support.
If you did not recognize the transaction on block-explorer or if you did not authorized, then kindly contact MetaMask support by following this article Do you think your wallet has been hacked? - READ HERE