Btrfs kernel bug -> duplicate file names

 △ nmiculinic@grid-ai ~ uname -a 
Linux grid-ai 5.10.36-2-MANJARO #1 SMP PREEMPT Tue May 11 19:38:44 UTC 2021 x86_64 GNU/Linux

btrfs has duplicate files at the same folder:

-rw------- 1 nmiculinic nmiculinic      563 Apr  4 10:13 pkcs11.txt
-rw-r--r-- 1 nmiculinic nmiculinic 15728640 May 28 21:44 places.sqlite
-rw-r--r-- 1 nmiculinic nmiculinic  2590600 May 28 21:45 places.sqlite-wal
-rw------- 1 nmiculinic nmiculinic    22643 Apr 16 00:33 prefs-1.js
-rw------- 1 nmiculinic nmiculinic    26241 May 28 21:45 prefs.js
-rw------- 1 nmiculinic nmiculinic    26241 May 28 21:45 prefs.js
-rw-r--r-- 1 nmiculinic nmiculinic    65536 May 28 20:50 protections.sqlite

example prefs.js; output of ls -l

 ▲ nmiculinic@grid-ai ~ cat /etc/fstab                                                     
# /dev/mapper/vg0-rootfs
UUID=46eafb11-4dff-47bc-91cf-045cb7c7a5c5       /               btrfs           rw,noatime,compress=lzo,ssd,space_cache,commit=120,subvolid=5,subvol=/       0 0

# /dev/mapper/vg0-docker
UUID=b1863d14-750e-4e2b-90fd-ae3db1d0745d       /var/lib/docker ext4            rw,noatime,discard      0 0

# /dev/mapper/vg0-home
UUID=fa5d84ff-1420-47b6-b76d-8d12fb44c7e2       /home           btrfs           rw,noatime,compress=lzo,ssd,space_cache,commit=120,subvolid=5,subvol=/       0 0

# /dev/nvme0n1p1 LABEL=ESP
UUID=0C5F-328D          /boot           vfat            rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,utf8,errors=remount-ro    0 0

# /dev/mapper/vg0-swap
UUID=6e5f027c-10a5-4050-b9fd-8d9ce962b2e9       none            swap            defaults,pri=-2 0 0