OK I seem to have found enough articles to conclude:
It’s perfectly fine to store html fragments and files in MongoDB as standard utf-8 encoded strings with a few caveats, noted in the MongoDB documentation “when should I use GridFS” (more on GridFS here)
GridFS is a specification for storing and retrieving files that
exceed the BSON-document size limit of 16 MB.ℹ️ NOTE
GridFS does not support multi-document transactions.Instead of storing a file in a single document, GridFS divides the file into parts, or chunks, and stores each chunk as a separate document.
When to use GridFS In MongoDB
In MongoDB, use GridFS for storing files larger than 16 MB.
Do not use GridFS if you need to update the content of the entire file atomically.