Am running the Linux Anki desktop Version 2.1.44 (b2b3275f). I am using the new scheduler, but have selected Legacy timezone handling, as I use AnkiDroid, which does not yet support the modern timezone handling.
All my decks have a unique identifier (Note ID). All unique identifiers are unique across the entire collection, so there is no chance of a card update affecting another deck.
One of my cards has some HTML in one of the fields, and whenever I update only a few cards, I import the CSV and all 5000+ cards are updated. This did not use to happen.
Other times, when I import into another deck, it is reported that all cards have been updated or several more cards updated than changes I had placed in the spreadsheet (which became the CSV).
The cards and decks don’t appear to have been damaged or changed in any unintended way, but the number of updated cards is confusing.
Some of these decks have been shared on Anki’s Shared Decks area.