Quota exceeded for write requests (but cloud says otherwise)

Question

I wrote a script for a client a long time ago that never had any problems until yesterday. gspread.exceptions.APIError....429, 'message': "Quota exceeded for quota metric 'Write requests' and limit 'Write requests per minute per user".... The user had not run anything for a day, and had done nothing dissimilar to what they had for the last year - number of requests was well below the max. I checked console, there is zero indication of reaching limits. It just seems to error for an unrelated reason, but gspread claims quota exceeded.

There's no reason for a quota error that I can see from my end, but I don't want to blame gspread.