I watched a lot of his campaign rallies, especially in the lead up to and through his first term, and he has always been the same. I follow US politics in general.
I would say he has degraded a bit for sure, but he has always been a compulsive liar, boaster, conflationist, revisionist...and dumb as a sack of spuds.
And it was always said, by many, that one reason he got elected was because of the media sanewashing him. And if everyone had been exposed to his actual words he said, then he likely would not have been elected.