Siri voice broken on Big Sur for Spoken Content (accessibility feature)

Hi,

I know the issue has been raised before, and am disappointed to see this still hasn't been fixed by Apple.

Basically when you activate spoken content using any Siri voice, the voice is crackling and the speed vaires.

Some users suggested right-clicking selected text, choosing Speech and Start Speaking, however this does not use the Siri voice, but rather the system voice which doesn't seem to have any issues.

Apple, it'd be great if you could fix the problem please!

Cheers