No, BYU's offense was not that high in either of those years. There is a reason that FEI is 6th or lower on the list of methodologies largely accepted by most in the CFB world.
It notoriously has a very flawed strength of schedule system based on team and opponent efficiency ratings, which can create circular dependencies. In other words, they calculate it by considering opponent quality relative to the team's own strength. This leads to inaccurate comparisons between teams with different schedules. So if a team were say, the 65th best team, and they played a whole schedule of teams just as good as they are (ranked 60-75), they could be listed as having a tougher strength of schedule than a if the best team in the country played a whole schedule comprising of the 25th-37th best teams.
It also does not count any offense in what is arbitrarily determined to be "garbage time". This admittedly is retroactively determined by the creator by "gut" feeling. In other words, if a team he feels that a team is dominating enough that the other team cannot win, then any offense after that point is not counted. As BYU is hardly ever in that situation, it skews more in their favor over more elite offenses. In 2021, BYU's bad defense heavily benefitted the offensive rankings in games such as the Virginia game where BYU scored 69 points, all of which counted due to defense giving up 49 points. Virtually all of their points counted towards their FEI that season, with the exception being Idaho State (FCS game). The model does not count FCS games, regardless of how good the FCS team is.
If you want to consider the FEI, I would recommend using a composite metric where FEI is averaged out with other methods that are more accepted and acknowledged.
When you do that, we are closer to #28-35 best offense in 2021, #54-66 in 2022, and #72-79 last year.
Keep in mind, 2021 we had Hall, Puka, and Allgeier. As I have stated in my other posts, those players can outplay Arod's liability by their sheer talent alone. Jaren's ability to be mobile and avoid turnovers covered up a lot both in 2021 and 2022. Similar to how having Hill and Jamaal covered up for a lot in that first 9 win season in 2016.
And again, I hope no one thinks Arod sucks. It is just that he has Kyle Shanahan syndrome. Great when we get breaks and are playing ahead with momentum, or when playing an inferior opponent. But if there is a game where critical game changing calls have to be made, or chess match adjustments created, you can count on him to get too cute, out think himself, and make a decision that puts our kids in a tough position to be successful. This leaves our players having to outplay this handicap. This is the reason that Shanahan has no super bowl rings (screwing the pooch in Atlanta and SF), and why I predict the 49ers will not win a super bowl as long as he calls the plays.
https://www.cougarboard.com/board/message.html?id=34260833
But, we are BYU. We do not have the killer instinct of some SEC or BIG power. We are not into firing people like that if they are "good enough". As long as we win 8+ games, Arod will always be "good enough".
But I agree with the OP, I find it very difficult to believe that Arod would ever be hired as the OC by a normally successful P4 school. If he were to quit, he would most likely find himself as a WR coach somewhere.