Questions on device trust

In general, device trust itself does not usually need to be manually re-established just because of a software upgrade.

What I normally see is that with a small version mismatch, active/standby failover may still stay up over the failover network, but config sync and mirroring are often unavailable until both devices are on the same version. Once both sides are upgraded to a supported matching version, those HA functions typically come back and the devices reconnect normally.

So for your second question, I’d say device trust is usually re-established automatically when the trust relationship is still intact and the temporary version mismatch is removed.

If trust itself was broken or corrupted, that is a different case, and you may need to rebuild trust manually rather than waiting for it to recover on its own

https://my.f5.com/manage/s/article/K20137641