The issue is plaguing every AndroidTV/GoogleTV box or stick with Android 11, please confirm if it's present in yours:
When using "Auto" on AV receivers with Dolby Atmos support: Dolby Digital, Dolby Digital Plus without Dolby Atmos and Dolby TrueHD without Dolby Atmos codecs are getting decoded as multichannel PCM when they should be passed through untouched to the AV receiver, the only one passing through correctly is Dolby Digital Plus with Dolby Atmos.
When using "Auto" on AV receivers without Dolby Atmos support: A constant Dolby Digital Plus signal is sent regardless if something is playing or not, when playback is on, the AV receiver always shows DD+ regardless of what's actually playing.
When using "Passthrough": This option sends every raw audio codec to a TV or AV receiver without checking if they actually support them, in this case, all the Dolby and DTS codecs are passed through untouched, BUT, it's not sending the Dolby Atmos metadata from Dolby Digital Plus and Dolby TrueHD, which means, they are played as regular Dolby Digital Plus and Dolby TrueHD codecs. I tested "Passthrough" with an old TV that doesn't support Dolby and DTS codecs and no audio was output, which means the option is working as intended.
Dolby TrueHD is not supported by every device, but it's worth mention it for those who do.
I REPEAT AGAIN: This is a problem present in the Android 11 source firmware that Google sends to every OEM, which means, the issue is present in every single Android TV box or stick unless the OEM already fixed it.
Nvidia Shield Pro here and works flawlessly