Btrfs Slow Write Performance, ?unusual or expected

I'm new to Linux. I just bought a new Gen 4 NVME to install Nobara Linux for general desktop and gaming use. I installed btrfs as it was the default FS and tested the drive. KDisk showed SEQ1M 3500 MB/s Read and 700MB/s Write. With CoW off, 2900 MB/s Write. In an ext4 partition KDisk showed 3500 MB/s Read and 3300 MB/s Write.

No compression and noatime made no different to write performance, CoW enabled/disabled was the only discernible factor.

I understand that btrfs will have a performance penalty, but this seems unusually slow. Can anyone verify on their Linux distro or know if this is a bug or kernel issue?