JSON log: `blob_details.xxxxxxx` being logged as fields

When doing a recent search in kibana, I noticed that in "Available fields" I see a bunch of fields and then... dozens (maybe more? scrolls is infinite) of json.blob_details.213q4324242 type fields.

I wonder if this was introduced via !132943 (merged), which adds a blob_id key to a value that is a hash.

This issue is problematic because it makes it really hard to find available keys in Kibana searches. There seem to be hundreds (or more?) of these json.blob_details.* fields.

Example query (see "Available fields" on left)

Screenshot: