Well, most Republicans fully support what happened on the 6th. This isn't surprising. What is surprising is that Democrats still think they can negotiate with these people.
I think most Republicans in Congress genuinely don't and their initial bipartisanship on this was legit. They are just constantly seeing and learning how many of their often self-picked, gerrymandered constituents do support January 6th, think the election was stolen, and are not willing to give their representatives an ounce of support (and in some cases worse) unless they keep the faith for Trump.