After drop local file on the tab strip:

In firefox everything works fine.
of course Allow access to file URLs enabled
I have the same issue in Brave, and access to file URLs is enabled.
This is an intended change in new Chrome, see crbug/1049604: both the content script and the main page context aren't allowed to fetch their own file:// URL anymore. FWIW there's an internal command line switch in Chrome 81+ --enable-features=RelaxIsolatedWorldCorsInFileUrlLoaderFactory.
We'll implement a workaround.
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This is an intended change in new Chrome, see crbug/1049604: both the content script and the main page context aren't allowed to fetch their own
file://URL anymore. FWIW there's an internal command line switch in Chrome 81+--enable-features=RelaxIsolatedWorldCorsInFileUrlLoaderFactory.We'll implement a workaround.