"DatastoreFileBlobDeletionIndex - Processing blobstore" takes long time and block the startup

SYMPTOM:

Customers open support tickets because they thought their upgrading was failed or in hang state.
The nexus.log stops updating after the following line:

2022-08-29 19:51:40,323-0700 INFO [FelixStartLevel] *SYSTEM org.sonatype.nexus.blobstore.file.internal.datastore.DatastoreFileBlobDeletionIndex - Processing blobstore <BLOBSTORE-NAME>, discovered file-based deletion index. Migrating to DB-based

EXPECTATION IN THIS JIRA:

As more customers will upgrade to 3.40 or higher and this can generate Urgent support tickets, would it be possible for the dev team to consider changing this to be a background / asynchronous task?
Or, at least, update our upgrade documentation to clearly alert customer that if "UUID"-deletions.index is very large, upgrading can take longer time.