The number of complaints about this on twitter has really jumped in the last few days. It appears that people are mainly complaining saying that they were not allowed board (or did not have a seat) and had to get a later flight. According to one, 10 people did not get on a flight to CR last night

Only 1 person has thanked Copa because of it: "made a couple of bucks for giving up my seat in Panama... thanks CopaAirlines". I asked them for details, but they didn't reply

Presumably from that last one, they are offering compensation. Unsure if they are seeking volunteers or just the last X people trying to board (or get confirmed seats) are told that they are not getting on - surely for flights to/from the US this would be against DOT regs?

I have 6 flights next week, none of them look anywhere close to oversold (Y9 B9 M9...9) for most of them