time for a test account and go through all the clients
more than interested if it is any special kind of action also, or logging in is enough to nuke it?
Discussion
If I remember correct Damus stuffs the relays list in the contact list, but there is no spec for that, in the past this would clear your (Damus) relays if you follow/unfollow someone in Nostur but I changed it to keep whatever is there so that doesn't happen anymore.
So if you are testing other clients, a follow/unfollow would probably do it. Nostur doesn't publish any relays at the moment, except for the ones you already have published as I'm still working to implement NIP-65 (Relay List Metadata)
reverse engineering
nostr:npub12262qa4uhw7u8gdwlgmntqtv7aye8vdcmvszkqwgs0zchel6mz7s6cgrkj just told me he thinks Damus might the culprit. He’s seems some odd stuff going on with dropped relays.