Large number of connections with Mongoose and Vercel

I’m still encountering this issue about every 2 days, usually early in the morning (Pacific time). It lasts for a minute or two. There’s a spike in connections and most of my queries are exceeding the 10s timeout on Vercel. It does seem like MongoDB successfully connects (see screenshot where I log the successful connection). The queries being run in these functions take < 200ms normally. Note that the Mongo connection is successfully cached when running normally. For some reason during these weird spikes, it tries to create a connection on each function request.

Any suggestions on how I could debug this?