Ask HN: How to log long JSON messages

The system I am working on is receiving huge (200kB) messages and logging them, currently to opensearch, but we're planning moving to Loki. The team responsible for the migration warned us that logs longer than 200kB will be truncated or dropped (we're still discussing it). My question is: what do you use to handle long messages in logs? Our use case is to track down flows according to the logs (to find out what messages was given object handling based on)