How is ZFS and/or BTRFS working for you on Linode?

I'm going to be shifting cPanel installations to Ubuntu 22.04 soon due to their official support and the fiasco over CentOS and the fragmentation going on with forks therefrom. It turns out that in one scenario I'm going to be having a lot of email hosting on Linode with many hundreds of gigabytes of email stored and likely going higher.

There's a problem with cPanel IMAP maildir where two additional functions are needed:

1. a filesystem more robust than EXT2/3/4 for enormous inode counts and
2. a filesystem that incorporates transparent compression due to some peculiarities with Dovecot's implementation on cPanel distributions.

Could you share your experiences with ZFS and/or BTRFS on Linode's infrastructure?

Linode's system was architected to support EXT4 and their support and/or input on using other filesystems beyond this are not within their support scope. They seem to encourage getting input from the community on experiences in this area, and so here I am - at their request - asking for some input and experiences. This would be particularly relevant for anyone using Ubuntu 20.04 or, more especially, 22.04.

Any benchmarks? Any observations or anecdotes?

Ultimately it appears a couple of other hosting providers may support these filesystems more officially, but I've been with Linode for a very, very long time and I would prefer to keep my infrastructure under a single umbrella vs jumping ship on some pretty significant architectural changes.