[FireMonkey] Somehow userscript interferes with sites' favicon

[Purfview]

Somehow userscript interferes with sites' favicon.

Userscript: https://github.com/Purfview/IMDb-Scout-Mod
Site: https://www.imdb.com/title/tt0088247/reference
Relevant link: Purfview/IMDb-Scout-Mod#180

Issue:
IMDb's favicon in a tab blinks multiple times and changes to some random icon from the script.

[erosman]

FireMonkey has no function relating to a site's favicon. The favicon change relates to the userscript.

[Purfview]

The userscript has no function relating to the site's favicon too and bug doesn't happen with any other "Monkey".

Here how it looks:

[Changes to a random image from the script, sometimes in the end it changes back to the original]

Here that icon starts as variable: IMDb_Scout_Mod.user.js#L8754
Here that icon ends going to the custom .LetterboxdUserRatingImg element: IMDb_Scout_Mod.user.js#L9114

[erosman]

I also noticed the favicon change but without checking the userscript in detail, the cause is unclear.

If the userscript developer points out the reason and it is related to FireMonkey, I will fix it.

[Purfview]

I'm the developer. I don't see any reason from the userscript's side.

This - $('.LetterboxdUserRatingImg').attr('src', lboxd_icon); somehow changes the favicon.
LetterboxdUserRatingImg is custom unique element, it shouldn't interfere with the favicon.

[erosman]

@Purfview Thank you for replying.

I have noticed Firefox sometimes changes favicon based on the HTTP request made from a page.
That should not happen but it sometimes does. I am going to have a chat with Mozilla engineers about it.

[erosman]

I have been doing some testing and here is the log of the code that requests the favicon.
I see a few favicon changes as the script executes.

load                          resource:///modules/FaviconLoader.sys.mjs:176:20
load                          resource:///modules/FaviconLoader.sys.mjs:563:70
loadIcons                     resource:///modules/FaviconLoader.sys.mjs:641:26
FaviconLoader/this.iconTask<  resource:///modules/FaviconLoader.sys.mjs:617:18
_runTask                      resource://gre/modules/DeferredTask.sys.mjs:347:18
_timerCallback/<              resource://gre/modules/DeferredTask.sys.mjs:318:20
_timerCallback                resource://gre/modules/DeferredTask.sys.mjs:337:9
_startTimer/callback/<        resource://gre/modules/DeferredTask.sys.mjs:185:18

Update

Filed XMLHttpRequest interferes with page favicon

[erosman]

Firefox bug is fixed in Firefox 120

See also:
Bug 1843267: Favicons defined in disconnected link elements (in document fragments) will be loaded and used as the tab icon