Of course I cannot work that one out.
Only the club can shed any light but I doubt they now have match by match details for 21/22 in the pre-Ticketmaster world? You may have email evidence of what he bought. They should have one number for each STH for each season - but if you say he should only have earned 350 that season not 610, that doesn't leave you any better off because the number carried forwards is zero whatever it should have been.
The question you might be better off asking is, do the points now on the account now accurately reflect what he has gathered over the last 4 years - August 2022 onwards? Just in case somehow they have deducted points from a different season somehow. They may be able to tell you what the remaining totals are for each season, and you can challenge any if it appears to be too low.
Good luck!