Muslim here. Mary is, in fact, not venerated in Islam in the way Catholics use the term. She’s praised in the Quran, sure, and is considered a Very Good Person, but so are many people. Islam is considered heresy in Christianity because it rejects the Trinity (according to Islam only Unitarians have the slightest clue what they’re talking about), accepts Muhammed as a prophet and rejects parts of the Bible as corrupted.