When looking at sets and filtering to "Expansion" there is set entry for "Alchemy: Innistrad" however none of the other Alchemy sets appear in the filtered list, I believe that the Alchemy sets shouldn't show up as expansion sets.
"Alchemy: The Brother's War" doesn't have a set symbol
"Alchemy: Dominara" doesn't have a set symbol
"Alchemy Horizons:
Baldur's Gate" doesn't have a set symbol
"Alchemy: Innistrad" doesn't have a set symbol
Assuming you try to match the database with Scryfall:
The set code for "Alchemy: Innistrad" is "A22" but using scryfall's nomenclature it would be "YMID"
The set code for "Alchemy Horizons:
Baldur's Gate" would be "HBG"
Alchemy modified cards are counting against the collection percentage. Is there a way to remove those cards from the calculation?