According to The Hollywood Reporter, the actors who played the characters Monica, Rachel, Phoebe, Chandler, Ross and Joey earned between $2.4 million and $3 million each.
Perhaps that figure is much less than the large sum they charged during all the seasons of the emblematic series. In those years the actors received up to a million dollars per episode, each season was between 18 and 25 episodes.
https://www.youtube.com/watch?v=HRXVQ77ehRQ
But considering that it was only a full-length special, the result is more than profitable for WarnerMedia.
The curious thing and what reinforced the union of the protagonists, was that from the second season a kind of mini-union was created to demand that the six protagonists could charge the same. Initially, each actor charged $22,500 for each episode.