Yes, seat upgrades. On Ryanair. All of the seats in different parts of the plane had different prices if you wanted to 'upgrade' - exit rows, front of the plane, etc etc - online. These prices (for the same seats) went up and/or down when the page was refreshed. This was for the return journey...
It was nothing to do with that more a complete failure of the check-in system for a big group and an inability of the staff to properly deal with it.
Then a seemingly random approach to seat upgrade prices. To the point where people refreshing their screens when trying to check in would get...
I came here to say exactly this!
I went about 20 years between Ryanair flights when I went out of Luton in September. I think it's got worse in those two decades!