GSI index survive a bucket deletion in deferred build edge case

While doing integration testing of index creation in the Java SDK, I came across what I think might be a bug (albeit in an edge case).
I create indexes on adhoc buckets, meaning that a single integration test is given a dedicated bucket for its duration (quite short, a few seconds). The bucket is then immediately destroyed. The tests create GSI index(es) and verifies the SDK API behavior.

At some point, I use the defer feature and trigger the build of 3 deferred indexes.

It looks like some times, most probably when the test finishes before the build has ended, the indexes survive the bucket's removal.
When I relaunch the test, it recreates a bucket with the same name but the index creation fails right away with the error "index already exist".

Looks like all indexes are already there and pending indexes keep that status indefinitely.