All the ones I've seen are quite recent, 2023 creation dates. Your "fieldmilestone" is one such.
Obviously they're not literally all the color+feature+company pattern but I don't think they're just reusing old "real" domains either.
As for not getting spam filtered, using a big pile of new domains with no web presence probably has the reverse effect so I don't think that's the intention here. Also I think as it's described, these emails aren't really sending messages to people, they're there to receive emails from Ticketmaster or similar entities when you go to transfer though them.