Created attachment 184359 [details] A Confirmative Screenshot # SUMMARY When https://addons.mozilla.org/firefox/downloads/file/4298512/plasma_integration-1.9.1.xpi is enabled in `firefox-142.0-1.fc42.x86_64.rpm`, `/html/body/div/div/main/article/section[2]/div/ul/li[10]/section/section/aside/div/details/p` of about:debugging#/runtime/this-firefox:~:text=Reading%20manifest:%20Warning%20processing%20key:%20An%20unexpected%20property%20was%20found%20in%20the%20WebExtension%20manifest reports: > Reading manifest: Warning processing key: An unexpected property was found in the WebExtension manifest. # STEPS TO REPRODUCE ~~~sh #!/usr/bin/env sh sudo dnf5 --refresh install firefox-142.0-1.fc42.x86_64 -y && \ firefox 'https://addons.mozilla.org/firefox/downloads/file/4298512/plasma_integration-1.9.1.xpi' firefox --new-tab 'about:debugging#/runtime/this-firefox:~:text=Reading%20manifest:%20Warning%20processing%20key:%20An%20unexpected%20property%20was%20found%20in%20the%20WebExtension%20manifest' ~~~ # OBSERVED RESULT > Reading manifest: Warning processing key: An unexpected property was found in the WebExtension manifest. # EXPECTED RESULT This warning shouldn't be displayed. It isn't for any others. # SOFTWARE/OS VERSIONS > ~~~ > Operating System: Fedora Linux 42 > KDE Plasma Version: 6.4.4 > KDE Frameworks Version: 6.17.0 > Qt Version: 6.9.1 > Kernel Version: 6.15.10-200.fc42.x86_64 (64-bit) > Graphics Platform: Wayland > Graphics Processor: AMD Radeon 780M Graphics > Manufacturer: Framework > Product Name: Laptop 16 (AMD Ryzen 7040 Series) > System Version: A7 > ~~~ # ADDITIONAL INFORMATION Ascertained whilst debugging https://bugzilla.mozilla.org/show_bug.cgi?id=1984438#c4:~:text=2025%2D08%2D22%2018:25%20UTC-,%23c1,-This%20recurs%20even.