Ted Ts’o sent out the EXT4 updates today for Linux 6.11. He explained in that pull request:
“Many cleanups and bug fixes in ext4, especially for the fast commit feature. Also some performance improvements; in particular, improving IOPS and throughput on fast devices running Async Direct I/O by up to 20% by optimizing jbd2_transaction_committed().”
If you want my answer, this video sums it up pretty good: https://www.youtube.com/watch?v=x9qCqRTEVz0
More recently fedora pulled this move which causes headaches to everyone: https://gitlab.com/gnuwget/wget2/-/issues/661
To this day I notice that there is some skepticism with Btrfs, and I think it is because fedora also pushed it early.