This has been every transaction since March 18 and is ongoing, even though subscriptions are being renewed and I'm getting paid. Stripe reports a webhooks error rate of 100% in the last 7 days. The last successful response (200) was March 16.
Ah - I just looked more closely at the response from my site in webhooks log. The error is "Error: 0 Call to a member function getType() on null"