We aren't aware of this being a current issue. Some things you can try to troubleshoot this type of issue:
1. Remove the Hulu channel from the Roku home screen. Restart your device from Settings>System>System restart. Once the device reboots, add the channel back again and see if this clears up the issue.
2. During playback of any content, press the * key to see if a 'Volume mode' is enabled. If so, try turning this feature off.
3. In Settings>Audio>Audio mode, try selecting 'Stereo' and then play the title again to see if the issue persists.
4. If your Roku device is connected to any A/V receiver or soundbar, try connecting your device directly to your TV.
Keep us posted from there. If you're still running into an issue, I'd recommend contacting Hulu support to report the issue and request additional help: https://help.hulu.com/s/article/how-to-contact-Hulu?language=en_US
Roku Community Manager