No official resolution, yet, that I have heard. I had to update my API calls with the appropriate date info, and provide better filtering for bad product info, but I still occasionally have the 520 error pop up.
Throwing my hat into the ring as well on this one. I've been getting on average, 2 of these 520 Origin errors per day (sometimes it's 520 Unknown Status which is a weird one). There's no pattern at the moment in terms of endpoint other than the fact that I only get it from the GraphQL API.
I'm about to add a retry for this as I didn't have it in my retry list previously.