Created attachment 141547 [details]
Error

SUMMARY
In the snap Chromium browser, on installing the Plasma Browser Integration addon it throws an error and doesn't work.

STEPS TO REPRODUCE
1. Install the Chromium browser ('apt install chromium-browser') 
2. Install the Plasma Integration addon (https://chrome.google.com/webstore/detail/plasma-integration/cimiefiiaegbelhefglklhhakcgmhkai/related)
3. Click the addon's icon in the titlebar

OBSERVED RESULT
See attachment; 
'Failed to connect to the native host.
Make sure the 'plasma-browser-integration' package is installed correctly and that you are running Plasma 5.13 or later.

Specified native messaging host not found.
Visit project wiki page for more information'

EXPECTED RESULT
It should work properly

SOFTWARE/OS VERSIONS
Operating System: KDE neon 5.22
KDE Plasma Version: 5.22.5
KDE Frameworks Version: 5.85.0
Qt Version: 5.15.3
Kernel Version: 5.11.0-34-generic (64-bit)
Graphics Platform: X11

ADDITIONAL INFORMATION
The project wiki page leads to https://developer.chrome.com/docs/apps/nativeMessaging/#native-messaging-host-location and as in this Chrome doc the relevant file *is* present under /etc/chromium/native-messaging-hosts/ so I don't think that's the problem.

Side note: this bug is very similar to https://bugs.kde.org/show_bug.cgi?id=396525 but I don't think the rationale for closing that bug applies here, because I'm using stock KDE neon, and the stock Chromium browser package found in the default repos.