@Brandon ***********
A mistake by Thailand Pass would absolutely not be the airline's responsibility (just as it wouldn't be their responsibility if an immigration officer at a port of entry determined that a visa had been issued in error).
The problem is that Thailand announced with great fanfare that holders of Thailand Pass QR codes would only need the code and the PCR test result for entry, but failed to have IATA update the Timatic database to reflect that. So you now have airline personnel being told by their computer that they have to check the same documents for Thailand Pass as they did for COE, even though that isn't the policy of the Thai government at all. The issue has been pointed out again and again since TP began on November 1, and Thailand hasn't even commented, let alone done anything about it.