I don't doubt there are a good number who were attending BYU and got those scores, but the percentage likely isn't as high as you might think. It may be that you studied with that group, so there was a selection bias.

BYU Fulton College of Engineering has 4000 students. A 2020 report said that for BYU admitted students that the composite ACT score of admitted BYU students was 26 for the 25th percentile and 31 for the 75th percentile. Nationally, the 25th percentile on ACT is 14 and the 75th percentile is a 25. So, the crop of BYU students is significantly better than the national average (we already all knew that based on how hard it is to get in). The engineerings might even be a bit above that.

However, nationally a 35-36 is the top 1% of all scores. Even if every single one of BYU's 35-36 was in the college of engineering and even if 10% of all engineering students got those scores, there would be about 100 in each graduating class spread across 6 different departments.

I wouldn't be surprised if there were a disproportionate number of 33-34's, but I doubt there are a large number of high 35-low 36 ACT (or SAT equivalent) students at BYU.