Katie Couric Calls Lauren Sanchez's Vogue Cover in Wedding Dress 'Tacky'

Lauren Sanchez's friends and family have been cheering her on all week as she ties the knot with Jeff Bezos ... but, at least one famous face is throwing shade -- and, blasting her high-end dress.

Katie Couric chimed in on Lauren's Vogue cover ... putting out a comment full of scorn on a post shared by John F. Kennedy's grandson, Jack Schlossberg.

On the post, Katie wrote, "Welcome to the eighties—when big hair and conspicuous consumption ruled. Apparently tacky is back."

It's a pretty brutal takedown -- no bride wants to be called tacky in their wedding gown ... but, it's especially cutting given how excited Lauren was about the dress in her profile.

The dress is a Dolce & Gabbana gown with a high-necked, hand-appliquéd Italian lace ... the first evening dress Lauren's ever worn that's covered her cleavage, she told the outlet. She called it "so elegant, it’s timeless."

Bezos and Sanchez married on San Grigorio Maggiore -- an island in Venice -- Friday in front of family, friends ... and some of the world's biggest stars.

Sydney Sweeney, Orlando Bloom, Oprah, Tom Brady, Gayle King, Usher, Kim Kardashian, Kylie Jenner, Kendall Jenner and many more celebs came out to celebrate the couple ... though the event's also drawn numerous protesters.

Katie's clearly not jumping on the train of support for Lauren and Jeff ... and, we doubt she's getting an invite to the vow renewal in the future.