Are you trying to listen in Dolby surround on a stereo setup? Disney+ defaults to surround sound and you’ll lose some audio channels if your speakers are stereo
Channel issues are like 90% of issues like this, but it's not always user error. Often a cheap production will just ship the front left + right channels as the stereo mix, instead of down mixing all the left + center channels into the stereo left etc. This is endemic in back catalogs on streaming providers where the catalog is a bulk assets that nobody reviews and is passed around between companies that don't care about the quality they deliver to each other.
User error but blaming the service to make an ideological point.
The dialog is just fine if you have a surround sound system or spend 5 seconds once to select stereo sound. Importantly, the dialog is still missing in the torrent versions taken from the surround sound stream because the same problem occurs. You only get the missing dialog in stereo if you download the stereo rip.
Disney+ defaults to the sound settings passed to it by the user's TV or device. It doesn't default to surround sound unless the user sets their TV or Roku or other device to surround sound.
And either way...it's the programmers at fault here. Very hypocritical for tech bros to pirate someone else's content when it's their own brethren that created the problem they're using to justify their piracy.