I often see, in both newer and older files, that Komga doesn't recognize or scan them correctly.
More often than not, rebuilding them corrects the error. This option will rebuild all files in a directory (RAR/CBR/ZIP/CBZ --> CBZ)
If the app fails to unpack a CBZ file, it will attempt to extraxt using RAR. I have encountered files where they were CBR files with the extension incorrectly renamed to CBZ instead of being properly converted. The app will account for that during any unpack/re-pack operation.