Immich isn’t a library (the main use case for semver is dependencies that will be pulled into other projects) and as far as I know they don’t state that they use semver.
It only affects undocumented behavior, no documented behavior is being broken.
If you want to consider breakage of undocumented / unintended behavior as a major change, then every bug you fix would require a major version bump, since when you fix something you are essentially breaking compatibility for anyone who might have possibly relied on the existence of that unintended behavior.
Immich isn’t a library (the main use case for semver is dependencies that will be pulled into other projects) and as far as I know they don’t state that they use semver.
But it is a service that clients connect to via an API.
The API specification is unaffected by this.
It only affects undocumented behavior, no documented behavior is being broken.
If you want to consider breakage of undocumented / unintended behavior as a major change, then every bug you fix would require a major version bump, since when you fix something you are essentially breaking compatibility for anyone who might have possibly relied on the existence of that unintended behavior.