Is the salary received by the applicant in the third month permissible or impermissible, knowing that he only worked for 7 days but was able to obtain an attendance record for 30 days, and that this grant is governmental and conditional on attendance, but has become perfunctory due to chaos?

A Muslim must fulfill the condition he committed to. Therefore, you are entitled to the grant only for the days you worked. Any excess must be returned to the responsible party. If it is impossible to return it or there is a fear of its loss, then spend it on the poor and needy to absolve yourself of responsibility, not with the intention of charity.