Luke 11:27-28 is commonly used to argue against the veneration or praise of Mary as Jesus appears to shoot down a woman's praise of her. However, a deeper look demonstrates why this is misguided.
1)The woman's response is not some novel way of praising and agreeing with the message of Jesus, which is literally made in praise of his parable of the unclean Spirit. Praising a person's mother in that manner is said by Jews to praise the son. This is clear from Genesis 49:25 and Proverbs 23:24-25. The Jewish document, the Pesikta Rabbati 27:2 also states this.
2)Luke himself accepts positively the praise of Mary earlier on the gospel such as in Luke 1:42; 48. Mary herself also says that "all generations will call me blessed" and this praise demonstrates this proclaimation in action
3)In Greek, menoun(rather) which is a rare Greek particle, carries the meaning that is fitted as "yes…but" which literally means Jesus accepts the woman's praise but also emphasizes that true discipleship comes not by hearing but doing which points to Mary as one example of this given what we get earlier.
Given these, Luke 11:27-28 cannot be used to argue that any praise of Mary is refused by Jesus.