I didn't get to see the game (ESPN Gamecast is very frustrating), but from what I "saw" toggling between Gamecast and the box score, this was a well-deserved win for Coastal. They stymied BYU's offense and ran the ball down BYU's throat. Disappointing for me as a BYU fan, but the games are played for a reason. Liberty had the ball on the final drive last year in Provo with a chance to win, too. The other team prepares for the game, too, and sometimes they plan and execute better.
In BYU-ville, the sky is falling, but I don't see it that way. We've only gone undefeated once; going undefeated is a truly magical season. And, the magical seasons don't come out of nowhere. 1984 for us was set up by several one or two loss seasons previously (the Nielson/McMahon/Wilson/Young) years, which "set the table" for the national championship year. Simply being a previously lowly-regarded team that goes undefeated out of nowhere doesn't do it --- in spades now, with the BCS/Playoff system that was set in place because of what BYU did. So, having a one-loss season, even during this Covid season, still can play a role in "setting the table," but you have to have the long view, not the instant gratification view. The exact same applies to Liberty, Coastal Carolina, Cincinnati, etc. Several solid seasons, with bowl wins over teams like Alabama and Oklahoma, have vaulted similar teams like Utah, Boise St., and TCU into prominence.
I really hope that Hugh Freeze stays at Liberty and doesn't seek the allure of P5. a) Liberty really gave him something when they hired him when he was persona non grata, and b) you become very special and legendary in situations like what he has right now. Not going to South Carolina, Tennessee, Nebraska, etc. And the people who really follow the program will love you forever.
Other BYU fans might look past Liberty in future years, but I won't. I'm a little more mature and philosophical than most of them are . . .
Long-term, when the whole system realigns, I'm not sure that Liberty and BYU will be welcome. It was a real eye-opener what happened with the Big 12 (BYU's stance on sex outside of marriage --- homo or hetero --- was the reason that arose). The Pac 12 hates BYU because of the woke liberalness of those West Coast institutions (and our arch rival, Utah, has strived to be our polar opposite in terms of secular-ness, secular humanism, etc. for many years).