Because I like to personalise my Mac I prefer to use my own login wallpaper (instead of the one set by Apple).
On Catalina I followed this procedure and all was fine.
(indeed my spare Mac, on which I experimented with this, now refuses to boot without SSV disabled…)
(How) Can I change the login wallpaper, while keeping SSV enabled?
Note: this Mac has FileVault enabled, has multiple users configured, and is under MDM control…