One thing I would add to a modern backup strategy: a deferred offline copy
Sure it's bothersome to use the sneakernet once a month (manually copy data to USB stick and stash it somewhere), but when that ransomware hits (can happen on personal devices also), it literally can't access the offline copy, and try to encrypt that one also.
Immutable backup solutions are code and thus eventually defeatable from the remote attackers point of view. Offline requires physical access, and maybe a big enough wrench to get the USB stick's disk encryption PIN out of you.
Tape + Iron Mountain is difficult to beat for offline copies.
Surrendering just a little bit of absolute control over the physical media can dramatically increase the likelihood that it survives whatever apocalyptic event. I don't know that I've ever heard of tapes being stolen from Iron Mountain. Even if this happened, what are the odds that they would get all the tapes. Your tapes? It probably looks like the warehouse from Raiders of the Lost Ark in there.
Immutable backup solutions are code and thus eventually defeatable from the remote attackers point of view.
Yeah, but an attacker is unlikely to compromise both you and your storage provider at the same point. Many S3-compatible storage providers (e.g. Backblaze and Hetzner) support object lock, where you can lock objects for a certain number of days (and refresh locks if the objects are still used in recent backups). Typically object locks are implemented such that not even you yourself can remove the data from the account settings.
E.g. when I cancelled my Backblaze B2 account, I had to wait until the object locks expired before I could remove the remaining data and delete the account.
Arq on macOS has great support for object locks BTW.
I have a locker at my place of work where I store a few HDDs and USBs. These are the most up to date, but I also have others at my parents place and my in-laws. Gets troublesome keeping track of which ones are up to date as of what date. Good challenge for staying organised though, I've got a whole naming system and numbered hierarchy and scripts that run ordered by priority.
Well overdue for a refresh.