Since Tether is fully backed the chance is really small.
https://www.coindesk.com/markets/2021/03/30/tether-takes-ste...
"as noted later in the article the composition of Tether’s assets is not spelled out in the attestation"
Meaning they may be backed by loans or fraud coins or anything.
being able to pay out some portion of "deposits" is obviously not evidence of being "fully backed".
If you want evidence of being fully backed they have attestations on their transparency page that breaks down their assets.