From Spectrum back in March 2022
"At this time the Spectrum TV app doesn't carry the signal for Dolby Digital 5.1 surround. We do welcome and appreciate all customer feedback regarding service features, availability and customer interest in a specific product or service and will certainly document this feedback. You can use the following link
https://www.spectrum.net/support/category/tv to find any updates as well should this feature be added in the future. "
PS: I don't use the Spectrum app.