After fixing random_moveChunk_timeseries_updates.js to actually perform updates in SERVER-75985, it brings out an invariant failure in the bucket catalog.

This is the invariant:

"Invariant failure","attr":{"expr":"input.has_value()","file":"src/mongo/db/timeseries/bucket_catalog/bucket_catalog_internal.cpp","line":826

Based on the stack trace, it’s triggered during an insert.