Because you’re “sync”ing with the state of the repo. You’re not necessarily upgrading. Sometimes the repos have a lower version than what you have, so you would be downgrading in that case. Or sometimes you’re just using it to install a new package and its dependencies.
-u is upgrade. And -uu is upgrade or downgrade. It’s used to filter the packages that sync operates on, so basically you’re syncing any packages that have a different version than the repo.
-y for refresh? No idea. -r is root, so I guess it was already in use by the time someone added refresh?
Because you’re “sync”ing with the state of the repo. You’re not necessarily upgrading. Sometimes the repos have a lower version than what you have, so you would be downgrading in that case. Or sometimes you’re just using it to install a new package and its dependencies.
-uis upgrade. And-uuis upgrade or downgrade. It’s used to filter the packages that sync operates on, so basically you’re syncing any packages that have a different version than the repo.-yfor refresh? No idea.-ris root, so I guess it was already in use by the time someone added refresh?