I absolutely love what you haven't fixed in Magic: The Gathering Arena; Magic is a game powered by obnoxious rare and mythic cards with thoroughly unfun planeswalkers. The horrid wildcard system in Magic: The Gather Arena just perpetuates the spiral into unfun ... after four years of playing online I quit ... Sheoldred is just too obnoxious and the drafts are so dominated by Mystic Archive style artifacts that I just don't want to play anymore ... I used to always buy the mastery pass with real money but no longer forget it. Furthermore I do not appreciate or enjoy the descent into the worship of darkness as the driving force of Magic: The Gathering, since the return to Innistrad the flavor team seems obsessed with with portraying darkness as supreme and the dominance of mono-black only confirms this wretched design commitment. Fed up, Baldur's Gate 3 was an absolute atrocity and I will never buy another of your befouled products again.
Good luck and Good riddance.

You could fix a lot of the problems with the Arena wildcard system if you simply implemented the following rules for deck construction. You could do it only for Alchemy so as to do effect paper magic which does not suffer from the same problem that your digital product does ...
Limit of up to 2 copies of a mythic rare card to a deck
Limit of up to 3 copies of a rare card to a deck
No more than 8 total cards of type planeswalker in a deck subject to the rules above.

The Phyrexians dominating the storyline and having all the power cards has really spoiled Magic for me.