On one hand, it seems unlikely to be accidental. But, this year my kid’s name was left off the high school baseball team list on the website - there was just one name missing from the names in row 2 in the team picture. It was on the website so it was corrected when we pointed it out. I wouldn’t be shocked if this is what was used in the yearbook - my kid is homeschooled so doesn’t get the yearbook. I don’t think that the homeschooling is the reason that my kid was left out - I think it was just a fluke.
This same high school has a couple of special needs kids who are part of the cheer team. They cheer at games and everybody knows them. But, they don’t compete at cheer competitions. I wouldn’t be surprised if there are 2 different versions of the cheer team pic in the yearbook at this school, since there are effectively 2 different teams - one for games and one for competition.