Fabulist
Definition: a liar, a teller of stories or fables
In examples on the web, I found it used to describe both George Santos and Alex Jones (in addition to the Trump reference below), so it’s definition seems pretty obvious by context.
Why I Looked It Up
In Spooked: The Trump Dossier, Black Cube, and the Rise of Private Spies:
Like many reporters who had followed [Trump’s] long career, he viewed Trump as a con man, an inveterate liar, and a publicity-seeking fabulist.
I was curious if if had any semantic relation to “fabulous.” Sure enough, in that definition:
[the original meaning of “fabulous”] was “characteristic of fables” (a fable is “an invented tale”). In that sense, “the fabulous legends of Arabia” refers to legends based upon fable rather than notably excellent legends.
Postscript
Added on
In an article about George Santos:
A Republican-led House managed to purge a serial fabulist from its ranks…