I´ve found a bug in Cubase 12.05 as can see in the screenshot:
a track is send to a group track (named coro), it´s automated in certain parts to be active and not in others but though the send indicator is grayed out and the automation lane is ok (red circles) the group track is still active processing data (green circle)
The voz1 track is soloed so no other track is sending data to that group track.