It's one of the things I hate about big conferences. I prefer the old days when the PAC-12 teams did a home and away, but teams want two more non-conference games. For several years before this year, they didn't play one travel pair twice; this year, two travel pairs didn't play twice. This year UCLA, USC, Colorado, and Utah. Last year, they only played Oregon and Oregon State once. In the 21-22 season, they only played Arizona and Arizona State twice. In 2020 they only played Washington and Washington State once. In 2019 they only played Utah and Colorado once.
So looks like Utah and Colorado were due up for skipping the home and away this year. Not sure how going to play four teams once this year and the Covid year (where they played everyone in the league twice) affected the rotation.