The security index had a few "object" types with
"dynamic": true
However, this automatically creates a mapping for each field that is
created within those objects. This means that types are dynamically
inferred and "locked in" for future updates.
Instead we want "dynamic": false which will allow us to store a range
of fields in these nested objects and retrieve them from the source,
without creating mapping types for those fields.
Backport of: #40499
920024e06d