I understand the problem you are trying to explain.
Because I also use Trezor.
Later, I did a lot of research and learned.
The problem is.
If the btc that appears in the Trezor main balance does not actually appear in the previously sent btc address.
When you transfer BTC, the Trezor system sends the previously sent BTC to the place you sent it at the time of transfer.
But it creates a new BTC address and sends the remaining balance to it.
You see it in your Trezor balance.
When you buy previous BTC, you cannot see it because the remaining BTC is sent to the new BTC address.
Your BTC do not disappear. Again, the balance is in Trezor, but at the new BTC address where the system creates an automatic fork.