Index operation rejected with Service Not Available error / Master Node Failed in logs

We noticed an index op fail with the error: {"ok":false,"message":"The requested resource is currently unavailable."} today.

When investigating the server logs during this time, it appears as if the master node in our cluster has for whatever reason become unreachable and there was some kind of a recovery workflow happening (Apologies, I'm new to operating Elasticsearch, still learning the ropes).

Here are all the server logs from that time: ES Prod Logs · GitHub

Looking for suggestions for where to look to investigate what happened or to know if this something that typically happens and for insights from the logs.

We're using Elastic Cloud with a 3 node cluster.