snap does not mount system /usr/share/fonts dir

Some time ago I notice that fonts in firefox becomes ugly on several sites. I check font settings and there is only few fonts (DejaVu and emoji). Further investigation revealed that `/usr/share/fonts` dir is empty in snap
```
snap run --shell firefox
ls -l /usr/share/fonts
```
Also while run shell there is error `update.go:85: cannot change mount namespace according to change mount (/run/user/1000/doc/by-app/snap.firefox /run/user/1000/doc none bind,rw,x-snapd.ignore-missing 0 0): cannot inspect "/run/user/1000/doc": lstat /run/user/1000/doc: permission denied` but I think it is not related.

```
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu Kinetic Kudu (development branch)
Release: 22.10
Codename: kinetic

$ snap --version
snap 2.57.2
snapd 2.57.2
series 16
ubuntu 22.10
kernel 5.19.0-19-generic
```

I try to check same things on Ubuntu 22.04 and all fine there (and no error on run shell).

PS: By the way chromium snap have the same issue