That occurred to me, but seems unlikely for the following reason (and this is giving Blizzard some credit)
The game has a lot of cards and it’s very difficult to test every combination. Some stuff will be unbalanced, it happens. However, Anyfin Can Happen is one of the narrowest-use cards in the game (read: THE WORST arena draft card ever). It really only works in a hyper-specific deck type, which means it SHOULD have been very easy to playtest - and that playtesting would have had to include Murk-Eye because why on earth wouldn’t you?
So basically it seems unlikely that they ‘didn’t know’ that was a good combo - it’s obviously a good combo, it’s not complicated or unexpected!
Edit: also, on top of that, Anyfin Can Happen will one day be retired and that would no longer be an issue even if it was now, whereas Old Murk-Eye is gonna be perma-retired for all time, right?