My best guess is that Manchin and Sinema are relishing their power and their leverage by holding the future of legislation passage at their fingertips, and they intend to milk everything they can out of it so that they can brag to their constituents ahead of 2024.

I imagine they have informally joined with Susan Collins and Lisa Murkowski (the two GOP Senators who most often frustrate hard-line conservatives), behind-the-scenes, so they can PERFORM THE POLITICAL THEATRE of "negotiating" future deals...allowing leaders of each of their parties to claim partial-"victories" (however hollow they might be) under the guise of moderation.