Discussion: Do you tell people unsolicited parenting advice or nah?

Saw a dad at the grocery store yesterday with his baby in one of those baby carriers and I could see the carrier wasn't positioned super ergonomically. My gut instinct was to be like "hey man just FYI that might hurt your back" but I didn't wanna be that guy. Got me thinking though - in this community do we say something if we think another parent might be doing something that could be uncomfortable or bad for the kid? Or is that crossing a line? Looking for honest takes here