It recognizes that I have 349/355 available cards from the pack when it’s in deck-building mode, but it still says that I have a 90.7% chance of opening a new card. When I uncheck deck-building mode it goes up to 98% so clearly something is changing, but 90.7% sounds far too high and has anecdotally not been accurate to my experience opening the pack.
TLDR: We don’t know, but probably the percentages are wrong.
Someone earlier raised that the percentage is always showing 100%, and that’s also the case for me (regardless if deck building is on or off, and after opening multiple packs), so I’m actually surprised you are getting a number that might somehow make sense.
I’m now working on code improvements for these calculations that should also fix some issues currently present with the new pack.
But some problems (i.e. treating cards that appear in multiple expansions as the same) will need to wait for the storage model rework that Marcel is working on.