Glass Onion is likely worth watching even for the flamboyant style (and Dave Bautista, he makes everything better ^^), but I did have issues with the plot:
1. The billionaire sends invitations to his friends, to go spend some time with him in his private island. But he has already murdered one of the group, and this bit of news would have circulated before they reached the island - if it wasn't for the sister of the murdered person asking the detective to contain the information from leaking. Now, the billionaire couldn't possibly know this would happen, so his friends would have already learned of the murder before reaching the island=> no one would want to spend time in a remote island with a murderer.
2. The reveal rests on very forced (and repeated) statements about how both the billionaire is "an idiot" and the group of his friends are "s..heads". This seems to be a way to excuse the glaring lack of logic with the main premise of the film (reaching the island) mentioned above. But it is lazy writing: "those people are cretins, and this is why no one thought of why all this wouldn't work out=> for them it might have worked out". One of the group is a (supposedly good) chemist, but I suppose even he is braindead so np ^^