Z06
I'm well aware of the longstanding audio issues with the DirecTV app on Roku, and what he actually is speaking is specifically large volume changes while using the app and watching content (read his post: "Getting variable sound problem when using DirecTV Stream channel. Will go from normal to very quiet, or from normal to very loud with extreme muffled static.")
This may be apparently confusing/unknown to you, but Volume modes apply to ALL audio output when enabled, not just commercials/ads, and not just while watching one show, or using one app - all output.
This shifting volume issue is the very reason that the Volume Leveling option exists to address.
Again, large volume changes can/do happen for ALL apps, especially those that have ad breaks, and especially those with inserted ads (from Roku).
This is not to suggest that enabling Volume Leveling (or other modes) will address other/all audio issues (like static) with the DirecTV app or any other app, or that there arent issues with Roku's audio infrastructure that may be contributing, but they may address the volume differential issues, hence its worth attempting to see if it can address the issue.