Sent USDT on the Wrong Network
USDT on TRC20, ERC20, and BEP20 are separate assets on separate blockchains sharing the same name — sending across networks doesn't convert the funds, it usually strands them.
Why this doesn't just "work anyway"
A deposit address is only wired up to recognize incoming funds on the specific network it was generated for. Sending USDT on a different network to that address means the receiving platform's systems generally have no record of expecting that transfer, even though the transaction itself may show as successful on the network you actually used.
What determines whether recovery is possible
Recovery generally depends on whether the destination address format is technically valid on both the network you meant to use and the one you actually used, and whether the receiving platform has a manual process for this specific situation. This isn't guaranteed even when both of those are true.
What to actually do
Contact the receiving platform's support with the transaction hash, the exact address used, and which network you sent on versus which one you intended. Don't attempt to resend or move funds further in the meantime — leave the situation as-is until support responds.