Only two possible explanations (or both): 1) the electorate as a whole is moving left. GA and AZ went blue, NC is almost there, and when Texas flips (maybe in the next 10 years?), Republicans will be permanently screwed.
and/or
2) Trump has done so much damage to the Republican brand that he lost states a Republican should never have lost (GA and AZ). Republicans may recover from the Trump disaster if they dump him and distance themselves from him, but that isn't happening. Trump will continue to suck up all the air in the room and dominate the party for at least the next 4 years. As he continues to lose more and more lawsuits his nationwide popularity dropping fast. If he runs again in 2024 the outcome for him (and all other Republicans on the ticket) will only be worse.