With Benthic Bloom equipped it would upgrade items again when you load in. Although, it doesn't do it infinitely just twice. The Benthic Bloom upgrades after the initial teleport, and then after quitting out and loading in again.
If it helps this is exactly what I did:
Had Benthic Bloom equipped on stage 4
Went to stage 5 and got my items upgraded
Quit out since my game stuttered
Installed stutterstunter (placing this here just in case its important)
With Benthic Bloom equipped it would upgrade items again when you load in. Although, it doesn't do it infinitely just twice. The Benthic Bloom upgrades after the initial teleport, and then after quitting out and loading in again.
If it helps this is exactly what I did: