“When you compare it to Tefillas Kol Peh where every paragraph is in a different font either different letter size, or bold to differentiate the paragraphs.”
Interesting.
I like the Artscroll siddur for the exact reason that it doesn’t randomly change fonts. It makes me nervous that one Halleluka is bigger than the next. or Berachos during shemoneh esrei randomly change size.
To each their own