Also the wrong way to implement an expiry data, since it'd work fine again when the day goes below 21 or month below 11, even if the year is 2021 or greater - which seems to be what happened if they only noticed it in November 2022 rather than 2021.
It might lead to a fault that appears more realistic - it'll go away for a bit in December before coming back again... if the engineers say the compressor's good but the computer fails it intermittently, that seems like a good point to get the manufacturer involved which is what they wanted to force
