Environment:
Browser / Version: Firefox Nightly 90.0a1 (🦎 90.0a1-20210525093431)
Operating System: Google Pixel 5 (Android 11) - 1080 x 2340 pixels, 19.5:9 ratio (~432 ppi density), Samsung Galaxy S8 (Android 9) - 1440 x 2960 pixels, 18.5:9 ratio (~570 ppi density)

Prerequisites:
ETP - Strict enabled.

Steps to reproduce:

1. Navigate to https://www.koket.se/italiensk-marang-se-gor
2. Observe the page.

Expected Behavior:
Page content loads.

Actual Behavior:
Page is blank.

Notes:

1. Screenshot attached.
2. The issue is not reproducible with ETP - Standard.

I see this error in the console:

TypeError: a.setPrivateMode is not a function

It looks like at least that function is missing in our Rich Relevance shim. We can investigate this and any other missing expected functions as part of bug 1713725.

There is actually more to the story here. They are getting the "TIPS!" and bottom gallery of recommended recipes from Rich Relevance, and the only way we could provide those would be to allow the user to opt into loading them from Rich Relevance. I'm not sure if accurately-placed placeholders are possible yet, but it seems they may be tricky. Either way, the basic breakage can be fixed relatively easily, so I'll target at least that much for bug 1713725.

This also seems to rely on improvements to our Google Publisher Tags shim (which are imminent).

This indeed seems to be working now with both the Rich Relevance and GPT shims, as per earlier comments. Once those updates land in Android Components, this ought to be fixed there as well.

Verified as fixed on the 8/2 Firefox Nightly build with GV 92.0a1 with Google Pixel (Android 10).

The issue isn't reproducible on Firefox 90.0a1 (2021-05-27) or on the latest Firefox Nightly 93.0a1 (2021-08-09) on Windows 10 x64, macOS 11.4 or on Ubuntu 20.04 x64 following the steps from the description.