That's a common, traditional form for non-lining numerals (https://en.wikipedia.org/wiki/Text_figures)

Turns out, Al Gore doesn't like it, either: https://www.typotheque.com/blog/gores_choice

FWIW, https://www.fontsquirrel.com/fonts/vollkorn, shows they have a choice of styles for numerals. But the half height I appears to be the default.

It does say I.I.I.I. Awful font.

uBlock Origin allows you to block remote fonts and use system fonts instead. You can selectively enable them on a per-domain basis, and, for cases like this, have them blocked them by default.

With remote fonts enabled on https://www.troyhunt.com/mmm-pi-hole/

  24 requests 3.12 MB / 3.06 MB transferred

And with remote fonts blocked:

  20 requests 2.96 MB / 2.90 MB transferred

It's not just ads you have to worry about.