GRUB search doesn't set btrfs subvolume

[Lyubomir Parvanov]

Hello,
I have the following btrfs subvolumes on  my btrfs boot partition:
sudo btrfs subvolume list /boot
ID 256 gen 300 top level 5 path @boot
ID 257 gen 301 top level 5 path @boot-snapshot
ID 343 gen 285 top level 257 path @boot-snapshot/67/snapshot
ID 344 gen 290 top level 257 path @boot-snapshot/68/snapshot

When I try to boot I get into the Minimal Bash shell. Apparently the
Kubuntu grub-mkconfig generates a grub.cfg which contains a call to the
search command in order to set the prefix environment variable. But as far
as I understand it doesn't take into account the btrfs subvolumes. The prefix
environment variable has the value of (hd0,gpt2)/grub right after dropping
into Minimal bash, and if i manually set the prefix to (hd0,gpt2)/@boot/grub
instead and execute normal, the system boots successfully. What seems
strange to me is that the calls to linux and initrd do in fact detect (and
set) the @boot btrfs subvolume.
See this screenshot too: https://i.imgur.com/yd11WQ1.jpg
I am also sending my grub.cfg file attached.

I hope that you'll be able to help me find a solution to this issue.

grub.cfg
Description: Binary data