Chrome 119 disabled "allow-insecure-localhost" flag which is used for testing of the SWF Chrome extension. It can be enabled if "temporary-unexpire-flags-m118" is enabled.

Currently the Github action machines contain Chrome 118 and the issue did not appear.
Locally with the Chrome 119 it is enough to use just "allow-insecure-localhost" from the tests but it might be needed to also add the "--enable-features=UnexpireFlagsM118" flag.

https://github.com/kiegroup/kie-tools/blob/main/packages/chrome-extension-test-helper/src/utils/tools/Driver.ts#L46

 chromeOptions.addArguments("--load-extension=" + chromeExtensionPath, "--allow-insecure-localhost");

How to enable "allow-insecure-localhost" flag in Chrome 119:

1. Open Chrome browser.
2. Open chrome://flags/ url.
3. Enable Temporarily unexpire M118 flags. chrome://flags/#temporary-unexpire-flags-m118
4. Restart Chrome
5. Enable Allow invalid certificates for resources loaded from localhost. chrome://flags/#allow-insecure-localhost
6. Restart browser.

Chrome can be also started from command line but the flags (chrome://flags/) are not displayed correctly in the ui. This is just problem of visualization in UI, the extension works correctly:

google-chrome --load-extension=/path/to/kie-tools/packages/chrome-extension-serverless-workflow-editor/dist --allow-insecure-localhost --enable-features=UnexpireFlagsM118