If you had accidentally joined a public group of untrusted individuals with your private main profile or an untrusted individual distributes your contact card without your consent.
If a third party had gained access to your private key (via a backup file, device physical access, malware or by accidentally adding the wrong device as a secondary).
Clicking an emergency button in the settings locally (or via the remote wipe mechanism) would accomplish the following:
Duplicate and fork the old account to old-1 that you synchronize across your devices and old-2 and old-3 that you do not
Remove all relays from old-3 and create a primary relay address
Create a new profile (at a fresh relay account with a fresh key pair)
Copy all user preferences (except credentials) and public fields from old-1 to new profile, such as name, bio, avatar, read receipts and theme
Generate a direct chat invite link to the new profile
Send invite link and a short template explanation (urging to verify out of band) to each contact using old-3 except to those who the user deselects
Add new profile as member to each group old-3 is a member of except to those which the user deselects
Post a short template explanation to each group with old-3, hopefully everyone should be aware of the modified primary relay address by now
Leave all groups with old-1
Back up all past messages on old-2 and import (in possibly slightly altered form) to new profile to mostly retain chat log
Clear and delete all groups and chats with old-1 to hopefully affect secondary devices coming online later
Remove all relays from old-1 and create a primary relay address for it (that hopefully nobody will know about) and ensure to never send any messages from it
Continue to monitor old-2 for a few months and if you catch messages from others, import it to the chat log of the new profile and reply with control messages from old-3 to update the relay address and leave groups
This is a convenience feature similar in spirit to clone chat in that it will not protect against targeted attacks:
The attacker discloses your private key to all of your contacts and groups or publicly.
The attacker overtakes some of the relay accounts you had used previously.
The attacker clicks the Clone profile button sooner than the original owner.
I found existing issues revolving around similar problems overly verbose, less focused and and not actionable:
I am not sure I am following the details here, but I support the general idea. If the attacker does not have the relay login password(s), this could be used to protect the account(s).