I enjoy a monopoly variant where every property landed on causes an auction regardless of who landed on it.

Oh, I like this a lot!

We recently picked up Monopoly with a new generation of players, and the flaws of the design were now apparent to adults. I think this could be a significant improvement.

Uh, isn't that the official rules? If a player lands on an unowned property, it goes to auction[0] EDIT: if the player doesn't buy it for the price printed on the board.

[0] https://officialgamerules.org/game-rules/monopoly/

No. Only if the player declines to buy it.

Corrected. Thanks. So the OP is playing with a variant where the original player landing on it doesn't get the first bite at the apple at the printed price?

Yes that's right