If you set the Lumin D2 to “Decoder + Renderer”, Roon will send the raw MQA (if no DSP / volume leveling / grouped zones) to Lumin, this way Lumin will display MQA, perform both MQA Core decoding and MQA Rendering.
If you set the Lumin D2 to “Renderer Only”, Roon will do the MQA Core decoding, send the MQA Core signal to Lumin, this way Lumin will display OFS and perform MQA Rendering.
Both are normal and comply with the latest requirements from MQA Ltd. and Roon signal path display.
Both are playing back MQA to their fullest extent. Although digitally the same, in case you hear a difference please tell me which sounds better to you.
To understand more please read