This is a super niche bug, however I've had it consistently when the conditions are met, ever since Mist Form rework.
Hoping I can shine some light on this bug here, to help out other high ping players.

ESO Currently has an automatic social ban if a player triggers some arbitrary speed hack suspicion criteria. I suspect this served a purpose [snip].
This has triggered consistently for myself, as well as other high ping players (250+) for a few select abilities, consistently for the last few years. Here are the conditions, that when met,
will almost always result in a social ban within a few hours of playtime.

1. You have high ping, so 250+.
2. The server is under moderate stress. From every case of this I've seen, it is limited to populated Cyrodiil campaigns.
3. You are using a ground target teleport ability, of which there are two I can 100% confirm this happens with.
- Vampire Mist Form (normal PvP).
- Arcanist Skill - Vengeance Apocryphal Gate (Vengeance PvP).

I cannot guarantee these are the trigger conditions exactly, however in every case of this I have experienced or heard about, these were the common denominators.
While on the topic, it is also worth discussing the quality of Zenimax Support's response to this. There is exactly one response you will ever get, always automated.


In addition to this, should the bug trigger shortly after the previous instance and you report the issue again, it will be permanently marked as a duplicate. Any attempts to
update a previous ticket will be stuck on 'waiting on agent'.


Due to the above, I have been social banned effectively 100% of the time since the beginning of the Vengeance test period, two weeks ago.
I imagine I am not the only player affected by the above cycle of outdated anti-cheat measures + [snip] support staff, rendering all core social features
of the game inaccessible. Historically, my social bans were well earned, so I believe some crowns compensation is due here to reinforce good behaviour.
[edited for bashing]