you updated to FP5.VT28 with a 2025-06-05 patchlevel before (while locked I think?), that rollback index is stored and honored when relocking again, doesn’t matter what you install (with a lower patchlevel) while unlocked.
If it’s the same year and month, Imo the 1st to 5th distinction matters, but can’t verify, so I’d wait for the next months patch level before relocking. If v3.1 /e/OS brings a 2025-07-01 patchlevel than you can go ahead.