SPFx webpart icons being replaced by default office fabric icon

Target SharePoint environment

SharePoint Online

What SharePoint development model, framework, SDK or API is this about?

💥 SharePoint Framework

Developer environment

None

What browser(s) / client(s) have you tested

[ ] 💥 Internet Explorer
[X] 💥 Microsoft Edge
[X] 💥 Google Chrome
[ ] 💥 FireFox
[ ] 💥 Safari
[ ] mobile (iOS/iPadOS)
[ ] mobile (Android)
[ ] not applicable
[ ] other (enter in the "Additional environment details" area below)

Additional environment details

No response

Describe the bug / error

For the last two months, the SPFx web part icon images are not being rendered. By default, the property officeFabricIconFontName is being defined as "Page" automatically upon generating the .sppkg file of said web part. With this, the value defined in the iconImageUrl of the preconfiguredEntries is being overridden by the Fabric Icon and therefore being ignored in SharePoint. Below, you can see the resulting issue:

As a workaround, the property officeFabricIconFontName can be defined in the preconfiguredEntries as an empty string to give priority to the defined iconImageUrl. However, this isn't a valid or acceptable solution since it requires the modification of this property in all existing web parts.

The main question is the reason why the officeFabricIconFontName all of a sudden has been given priority instead of the iconImageUrl?

Steps to reproduce

Deploy a web part to a tenant.
Open the toolbox to add a new web part.
Verify the defined iconImageUrl is missing and was replaced by the Office Fabric Icon 'Page'.

Expected behavior

The expected result was the intended image defined in the iconImageUrl to appear in the toolbox.

SharePoint / sp-dev-docs