“Breaks all compatibility [with emby]” was my interpretation of that. Not a huge deal either way but I’d definitely have been calling it 11 with this DB rework myself

Basically, yes. Forces plugins not to use potentially database-engine-specific SQL so that server admins don’t have to select their DB based on plugins for jellyfin being compatible.

I kinda agree here. https://jellyfin.org/docs/general/contributing/release-procedure/

Claims to follow semantic versioning, explicitly mentioning changes to plugin APIs as reasoning for a new major version.