Why do I get a broken seal on my root filesystem APFS?

I already found this practical question which might be a beginning of an answer:

Answer to FileVault reporting Sealed Brok… - Apple Community

On my system, I got this kind of output from diskutil:

### 18:57       noether:/       % diskutil apfs list
APFS Containers (4 found)
|
+-- Container disk1 C492EC11-0203-4F01-928A-DB1D85A937D8
|   ====================================================
[...]
|   +-> Volume disk1s5 6D9F6C55-5A78-46CE-A3F0-48E7B911E6EB
|       ---------------------------------------------------
|       APFS Volume Disk (Role):   disk1s5 (System)
|       Name:                      noether 1 250 Go (Case-sensitive)
|       Mount Point:               /Volumes/noether 1 250 Go 1
|       Capacity Consumed:         15321800704 B (15.3 GB)
|       Sealed:                    Broken
|       FileVault:                 Yes (Unlocked)
|       Encrypted:                 No
|       |
|       Snapshot:                  E7B5A378-DBBD-4D57-8EDB-FE378C260987
|       Snapshot Disk:             disk1s5s1
|       Snapshot Mount Point:      /
|       Snapshot Sealed:           Yes
[...]

I clearly understand that the line:

|       FileVault:                 Yes (Unlocked)

means that this volume is unlocked, because I opened it upon opening my session.

But I don't see what the line:

|       Sealed:                    Broken

means.

Disk Utility > First Aid doesn't detect any anomaly on this volume.

This is a problem I experience on macOS 11.7.8, nickname Big Sur. I think the question is the same for any version

of macOS supporting APFS format.

man diskutil

doesn't show the word seal or broken.

What did break this filesystem seal?

How may I fix it?