Btrfs was merged in 2009, but didn't gain wide acceptance until quite recently. Among the biggest distros, only Fedora uses it as default, and RHEL has actually dropped support. Even today, you can still find people claiming that they lost data because of it, though whether they are telling the truth I cannot say.
I'm not saying you should switch all your critical systems to bcachefs on the day it gets merged as you can never be sure about the absence of bugs (even the relatively simple ext4 had some data-eating bug a few years after introduction), but the path to "recommended filesystem" will be a lot shorter than btrfs.
At this point, I would already feel comfterable running bcachefs on my laptop – the only reason I don't is that I just can't be bothered running a custom kernel for it.
I haven't lost data on it, but my 8 drive Btrfs RAID6 filesystem locked up read-only on me, which wasn't fun. Switched to ZFS after that.
Only raid5/6 has known issues.
With mdadm, I don't get auto-repair on top of the checksumming.
It is totally understandable that if the underlying driver starts returning errors, btrfs (or any other filesystem) may be unable to provide access to my data; but I was not at all happy about having to reboot the entire machine.
(I must admit, it is possible that the "freezing" was happening in underlying block device driver code and not in btrfs. I don't remember if I ever checked wchan to see which it was. My impression from reading dmesg output was the issue seemed to be with btrfs.)
I did once have a similar experience with ZFS as well. Sigh.
A nice (and lone) data point regarding btrfs, though: My dentist told me that he was storing patient data using btrfs last year. :)
ISTR hours-long repair operations and a level of desperation that a lot of people wouldn't have had time for. This is assuming you didn't use its RAID or other features that definitely would eat your data.
(This is experience from 10 years ago when I was looking for the latest and greatest features to support a hosting platform)
Main problem with Bcachefs is its in unknown state. There was no major testing done on that. When some company (like Oracle or Suse) puts it through automated stress test matrix, it may do exceptionally well or completely fail.
For example Suse participated over 25 years on Ext3,4, ReiserFS/4, XFS, BTRFS.... This know how is not public!
Still a pretty good endorsement in my mind.