I think we both know that.
Some Catholics (undoubtedly a fewer percentage today than in times past) treat her as if she were functionally divine.
And some non-Catholics view any veneration as if the object is divine. And some NCs deny the way humans, including Mary, played a role in their own salvation, and that of others.
And when Catholics assert that, it is seen as equating God and the human, no matter how many times we contextualize it as the human being infinitely less than God.
They pray to her, hope for favors from her, and treat her as if she were omniscient and omnipotent.
If they do without recognizing that she is not a source of grace, but a channel of it, then they are in error.
The title "Mediatrix of All Graces" says that all divine blessings must come through her.
Yes. As all grace enters the world through Jesus, who entered the world through her. Understand, she is not given control of the graces. She does not create them, she does not control to whom they go, she does nothing and wields no authority or power that is not fully on loan from God and entirely in congruence with His Will.
And I'm not just saying that.
SD
Okay, but consider this. Everything comes from God. The Catholic petitions Mary, who petitions God for the favor. So the ultimate source is God. But then, there is a different stream of belief which says that God will grant anything that Mary asks, because he cannot refuse her. And if God cannot refuse Mary, then she does have functionally divine power.
she does not control to whom they go
Then why pray to her for graces? From a Catholic web site:
Prayer of Petition
O Ever-Virgin Mother of God and Mediatrix of Grace who art the House of Gold within which dwells thy Son, our Mediator, Jesus Christ, we humbly beseech thee to grant our requests for our salvation and the salvation of the entire world. (Here pause and make your requests) Keep us close to the Vicar of thy Son in the unity of the One, Holy, Catholic, Apostolic and Roman Church. Hear our prayer and grant the requests we make to thee.
Popular devotions such as this clearly suggest that Mary distributes the graces. And the writings of the popes I posted certainly don't contradict this.