I use Debian Trixie/Testing on a NVMe. I have a crypsetup, boot and EFI partition. Inside the cryptsetup partition is a LVM that hosts a Btrfs. No swap.

Yesterday the system reported the SMART issue nvm subsystem reliability has been degraded. Other resources agree that this is serious and the drive needs no be replaced.

Today I tried to prepare everything for that. In particular, I tried to free space so the disk image I was about to clone could be compressed better. For this, I ran btrfs subvol delete for like 60 whole-system subvolumes and after that fstrim. This was the first time I ran fstrim manually for at least a year. Executing fstrim took several minutes to complete.

After that I rebooted. Then I noticed that smartctl does not report this issue any more. Now the drive seems to be healthy again.

What does that mean? Did I fix the issue? Is this kind of error supposed to be flaky and I should migrate anyway?