Cross origin headers are not working with Netlify

I’m trying to run ffmpeg
(in-browser) script to merge the files on the go in client device via browser.

And I setup the below headers at public/_headers:

Cross-Origin-Embedder-Policy: require-corp
Cross-Origin-Opener-Policy: same-origin

Verified that it is appearing in build as well, as it appears under build/_headers after the build.

However I get the error in browser console:
Uncaught (in promise) ReferenceError: SharedArrayBuffer is not defined

This is related to cross origin requirements mentioned in their docs:

So, I’m blocked at this point why this error comes even if I mentioned required cross origin headers.
Or is it that this is not possible with Netlify ?