I'm curious... Is it possible that the 'loss' of patreons is that credit cards have expired and it takes a day or so for the cardholder/patron to provide updated credit card details?
This could explain the significant drop-off at month end and then an up-tick during the first few days of the new month.
I think I had mentioned this before, that's exactly what happens. Patreon bills on either the last day or first day of the month. Anyone who has payment issues for any reason (credit card expired, etc.) drops off the count that day.
However, Patreon sends them a reminder asking them to "re-up" their pledge or fix the issue. So, a few might do just that, and they then get added back to that count.
He's actually lost one more yesterday or today, he's at 503 right now.