I think there’s plenty of humor in the OT that is somewhat meta and dresses down the typical conventions of genre films. Maybe not to the extent of the ST but I find the humor in the latter trilogy to be a not unnatural extension. It’s funny because I’d say the attitude of “Don’t worry, even the characters in the movie know this is a bit silly” is something that can be found in the original film and one of the things I love about it. Obviously you take that too far and you’ve undercut the world you’re building but I truly am not sure where TLJ supposedly did that.

As to the question of earnestness, I think there’s a whole lot of it on display in TLJ, I would easily say far more so than TFA, honestly.

I personally feel like Solo was very much cut from the same cloth, if anything I’d say it’s the only one that maybe took the meta winks too far. Rogue One is definitely the lightest on comedy but it also happens to be the least fun Star Wars movie to watch by a mile - correlation inconclusive.