syzbot has bisected this issue to:

commit 14152654805256d760315ec24e414363bfa19a06
Author: Kent Overstreet [off-list ref]
Date:   Mon Nov 25 05:21:27 2024 +0000

    bcachefs: Bad btree roots are now autofix

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=171a52e4580000
start commit:   224e74511041 Merge tag 'kbuild-fixes-v6.14-2' of git://git..
git tree:       upstream
final oops:     https://syzkaller.appspot.com/x/report.txt?x=149a52e4580000
console output: https://syzkaller.appspot.com/x/log.txt?x=109a52e4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e55cabe422b4fcaf
dashboard link: https://syzkaller.appspot.com/bug?extid=76f13f2acac84df26aae
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14e8b5a4580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1155a898580000

Reported-by: syzbot+76f13f2acac84df26aae@syzkaller.appspotmail.com
Fixes: 141526548052 ("bcachefs: Bad btree roots are now autofix")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection