I started my reviews on desktop
had a bad card, so I deleted it
forgot the grab the content of a field to recreate it
decided to grab it on AnkiWeb so it went like this:
easy, easy, easy, easy, easy, easy, oh there is my card and its sentence field
going back to AnkiDesktop, without syncing obviously
finishing the reviews a moment later and then finally, syncing
→ the cards I had rated easy on AnkiWeb had added the rating along the others and anki didn’t ask which collection to keep/whether I wanted to sync up or down
Under normal circumstances, reviews and note edits can be merged, so if you review or edit on two different devices before syncing, Anki will preserve your changes from both locations. If the same card has been reviewed in two different locations, both reviews will be marked in the revision history, and the card will be kept in the state it was when it was most recently answered.
This happens, when anki detects a conflict or when you force sync
There are certain changes that Anki is unable to merge. These mainly relate to the format of notes: things like adding a new field, or removing a card template. When you perform an operation that can’t be merged, Anki will warn you, and give you the option of aborting the operation. If you choose to continue, you’ll be asked to choose whether to keep the local copy or the copy on AnkiWeb when your collection is next synchronized.
You can force sync manually, which will trigger the collection to upload/download
If you wish to force a full upload or download (for example, because you accidentally deleted a deck on one side and want to restore the deck rather than having its deletion synchronized), you can check the “On next sync, force changes in one direction” box in Tools>Preferences>Network, then sync as usual. (You’ll be given the option to choose which side you want to use.)