Ads are ABSOLUTELY the problem
There are so many ads that redirect to the app store that the app is UNUSABLE. Just leaving the app has the potential to clear what ever you were doing so any ad has the potential to send you back to page one. On top of that sometimes the apps actually CRASH the app.
Im fine with the ads at the bottom of the screen and ads spread across the entries. Unfortunately since those are blank 90% of the time and they seem to be broken, it appears that Pixiv has decided to bombard your phone with pop up ads that dont let you browse and crash the app instead.
ChairOfCheese about
pixiv, v6.2.1