I assure you, it’s not. OP is seeing what is most likely random fluctuation. Why on earth would UA choose to give its best prices to price-inelastic business travelers?

The internet has been abound with this type of advice for years — and fares keep going up. To the extent that any of these patterns are real — as soon as the pattern becomes public, the airline will go and change it. UA changes prices thousands, if not millions, of times per day. There is no single best time to buy airfare, and there probably hasn’t been in at least 20 years. The best strategy is to learn the market and strike when the price seems reasonable (and, with no change fees, you can keep checking afterwards to see if the fare has dropped, and capture the difference as a future flight credit).

OP: You’re probably running into some daily inventory adjustment. Maybe somebody was trying to set a job for midnight GMT and messed it up. In general, patterns are mostly in the eyes of the observer.