While Tuesdays and Wednesdays are typically the cheapest days to fly, Fridays and Sundays tend to be the most expensive, according to a review of data from travel websites including Google Flights

https://sites.google.com/view/alaska-airlines-mexico/home
https://sites.google.com/view/tap-portugal-es-pt/home
https://sites.google.com/view/qatar-airways-es-es/home