Yes, the issue is present in cswiki wmf.28. It does not seem to be reproducible in betalabs; for production the issue is present with the browser mobile emulator. The issue is present only when VE is an editor (which is a default editor for new users on cswiki.

In production there is kind of reverse order of features that should be presented:

Change 593925 had a related patch set uploaded (by Kosta Harlan; owner: Kosta Harlan):
[mediawiki/extensions/GrowthExperiments@master] Help panel: Check if guidance feature flag is set before loading mobile peek

https://gerrit.wikimedia.org/r/593925

Change 593925 merged by jenkins-bot:
[mediawiki/extensions/GrowthExperiments@master] Help panel: Check if guidance feature flag is set before loading mobile peek

https://gerrit.wikimedia.org/r/593925

I guess we want to backport this?

Change 594134 had a related patch set uploaded (by Urbanecm; owner: Kosta Harlan):
[mediawiki/extensions/GrowthExperiments@wmf/1.35.0-wmf.30] Help panel: Check if guidance feature flag is set before loading mobile peek

https://gerrit.wikimedia.org/r/594134

Change 594134 merged by jenkins-bot:
[mediawiki/extensions/GrowthExperiments@wmf/1.35.0-wmf.30] Help panel: Check if guidance feature flag is set before loading mobile peek

https://gerrit.wikimedia.org/r/594134

Change 594137 had a related patch set uploaded (by Gergő Tisza; owner: Kosta Harlan):
[mediawiki/extensions/GrowthExperiments@wmf/1.35.0-wmf.28] Help panel: Check if guidance feature flag is set before loading mobile peek

https://gerrit.wikimedia.org/r/594137

Change 594137 merged by jenkins-bot:
[mediawiki/extensions/GrowthExperiments@wmf/1.35.0-wmf.28] Help panel: Check if guidance feature flag is set before loading mobile peek

https://gerrit.wikimedia.org/r/594137

Mentioned in SAL (#wikimedia-operations) [2020-05-04T11:43:25Z] <tgr@deploy1001> Synchronized php-1.35.0-wmf.28/extensions/GrowthExperiments/modules/helppanel/ext.growthExperiments.HelpPanel.cta.js: SWAT: [[gerrit:594137|Help panel: Check if guidance feature flag is set before loading mobile peek (T251589)]] (duration: 01m 10s)

Mentioned in SAL (#wikimedia-operations) [2020-05-04T11:46:41Z] <tgr@deploy1001> Synchronized php-1.35.0-wmf.30/extensions/GrowthExperiments/modules/helppanel/ext.growthExperiments.HelpPanel.cta.js: SWAT: [[gerrit:594134|Help panel: Check if guidance feature flag is set before loading mobile peek (T251589)]] (duration: 01m 06s)

This was backported to wmf.28 and wmf.30. I've checked at cswiki, looks like it works to me.

Confirmed - resolved; checked on cswiki, wmf.28.

@Catrope @Tgr @kostajh -- a reminder to please post on this task the time period that the bug was in production.

The mobile peek was added in rEGREbcc0bd182b42: Guidance: Implement mobile peek which was first included in wmf.23, which was deployed on March 12. (868f78e is the only other somewhat relevant commit I can see, but that just moves code around and doesn't change loading behavior.) So it seems like the error might have started then. I'm not able to reproduce it locally though (something to do with ResourceLoader race conditions due to load.php being slow on Vagrant, I think), so I'm not 100% sure. Also, I understand why the peek would show up (it was executed whenever the help panel was loaded, as long as the geclickid tracking was active) but I don't really understand why it would show up in the weird broken gray version - it seems like all the content should have been loaded just the same even if we are in the editor. Possibly the editor overlay is on top of the drawer overlay (we have seen a similar issue with the homepage overlays) but then it would not be visible at all.

The fix was on May 4 as per T251589#6104205.

In T251589#6112500, @Tgr wrote:

Possibly the editor overlay is on top of the drawer overlay (we have seen a similar issue with the homepage overlays) but then it would not be visible at all.

That's indeed what's happening on my local setup. Now that I knew what to look for, I can confirm the issue was present in wmf.23. Still not sure why a part of the drawer appeared on top of the editor overlay in production, and whether that was the case for the full wmf.23 - wmf.28 period. The way it works on my local setup, there is no noticeable change during editing at all, and after cancelling the editor the whole page is grayed out and you need to click to get rid of it (the drawer tries to display but presumably being obscured by the overlay messes up the positioning so the content part is somewhere below the viewport edge). If you save, the grey layer is visible for a very brief moment, but then the page gets reloaded so it disappears.