I can confirm this. I just downloaded version 72.0.3626.121 and the extension works.
https://i.imgur.com/VtsMsfg.gif
So I noticed this issue today. Last week it was fine. I mean MangaRock still wouldn't load the extension if i open a manga from the site. But if i opened a manga from the extension it worked. I made peace with that. But today this is what I get. The extension tries to load before MangaRock has its way. Hopefully the gif is clear enough.
I'm using extension ver. 2.1.0
Chrome ver. 73.0.3683.86 (Official Build) (64-bit)
OS ver. macOS 10.14.4
PS. I was curious so I downloaded Firefox and the extension works fine on firefox.