Luke 1:28: And having come in, the angel said to her, “Rejoice, highly favored one, the Lord is with you; blessed are you among women!”
I don’t see anything in that verse to say that Mary was sinless. She was favored, she was blessed among women, but that does not say sinless.
Hail Mary, full of GRACE...
There is more than one interpretation of the Bible.
Luke 1:28Revised Standard Version Catholic Edition (RSVCE)
28 And he came to her and said, “Hail, full of grace,[a] the Lord is with you!”[b]
Footnotes:
Luke 1:28 Or O favored one
Luke 1:28 Other ancient authorities add “Blessed are you among women!”
Also: Luke 1:28King James Version (KJV)
28 And the angel came in unto her, and said, Hail, thou that art highly favoured, the Lord is with thee: blessed art thou among women.
Also: Luke 1:28Douay-Rheims 1899 American Edition (DRA)
28 And the angel being come in, said unto her: Hail, full of grace, the Lord is with thee: blessed art thou among women.