TIL Proton dropped their maximum supported security keys (some time after mid-August 2024) from 8 to 4 keys?! (Notice the tiny "8 out of 4" label, because I had registered the maximum 8 keys)
I suspect my current config will be stable until I need to explicitly delete a key, in which case I won't be able to add a replacement unless I delete five keys. 😡
Sometimes pure naive thinking -- that fewer keys = more attack surface (which poorly maps to some threat models, robbing the user of autonomy over those models).
Sometimes because there are (brief) performance thresholds, because the set of all potential keys is enumerated during the initial presentation of the key. Google's informal "starts to get materially worse for the user" (but not enforced) is ten keys.I think there's a half-second delay with ten keys, IIRC.
Royce Williams
keschi 
Θ
Henryk Plötz
Adam Katz