I am developing an extension called “Bing Chat on Chromium” that uses the declarativeNetRequest API to modify network requests. The source code is available here: https://github.com/claudio4/bing-chat-on-chromium

I have noticed that there seems to be a problem with this API on Opera and Opera GX. Specifically, it doesn’t seem to overwrite the header nor does it add additional headers when I use the modifyHeaders action. This works fine on other browsers that support this API, such as Brave, Chrome, Chromium and Vivaldi.

I have used the ‘declarativeNetRequestFeedback’ permission to check where the rules get triggered and indeed they do. However, the headers are not modified as expected.

Is this a known issue or a bug? Has anyone else experienced this problem? I would appreciate any help or feedback on how to fix this.

Thank you.