@Bruce ********
pardon me ...but how does one fail a Thai language test ?
Did you actually attend classes or did you buy the Ed visa without classes needed.
Or you chose to change to COVID extension rather than pay for the extra added fees for the Ed Visa extension costs ...
Enough said....no answer needed.
Before your current permission stamp ends in March...ask your Thai Immigration office IF you can get a COVID extension? Do not apply unless they say you can.
Good Luck.