A renewal that fails on the 28th is usually next month's money

When a card is declined on renewal day, Stripe retries it over the following days or weeks, on the schedule in your Billing settings, and many of those retries go through.

Say eight $99 renewals fail on September 28. Five recover by October 5 and reach your bank on October 7. The invoices still carry their September date, so a report by invoice date shows $792 of September revenue. Your bank shows $495 of it arriving in October. The three that never recovered, $297, are simply not there.

Compare September to the bank and you are $792 short; October is $495 over. Neither tells you three customers are gone.

Count failed renewals by what happened to them, not by the month they were billed. Smaller payouts from retries are one of the reasons in why a Stripe payout does not match your sales.