My compound is south of inbetween Canada and Scandinavia. As is yours. Which does not mean we are very close, but close. Just 370km, as the crow flies in the tundra. A woody place near Amsterdam.
Interesting, that track demonstrates the same issue on my Bartok as well when played back via Mosaic (left pic), but works properly when played back via Roon (right pic);
ps: Same issue on my Vivaldi Upsampler as well.
Same here on my Rossini. MQA fine via Roon (both sourced via Tidal as well as from local files - I’ve got a few MQA-encoded CDs ripped and stored on my NAS).
However, MQA files (Tidal and local) played via Mosaic: shows up as MPEG, at seemingly unfolded data rates but not recognised as MQA by the Rossini.
Consistent with what happens on a Bartok.
Would be interesting to see how this behaviour is on a Vivaldi stack - MQA duties are split between Upsampler and DAC on such a stack.
The part I do not understand is that the OP made it clear that this issue did not exist " until a few days ago". There were no reports of it prior to this week. Now we are seeing other examples so it is not confined to the OP.
If it is a purely Mosaic problem how did the change occur? The last time Mosaic was updated was in December 2020. Mosaic does not ( AFAIK) update itself automatically as updates require action from the user. We are still at v.1.1.1. the same as when it was showing MQA correctly according to the OP.
There is an answer ( or partial answer) to this in Anup’s postscript to his message above :
Pete, I think the reason reports are only now emerging is because the problem seems to manifest only with some very specific MQA tracks. Most of the MQA tracks on Tidal work just fine with Mosaic.
Then if that is correct it could be possible that the problem lies outside of Mosaic as the app cannot distinguish between tracks nominally of the same technical type.
I wonder if this will turn out to be an error at the record label. It only requires a junior staff member to mistakenly type MPEG and not MQA on the order to the production studio for the order to be fulfilled and the result distributed to Tidal. Nobody is going to actually play it to check. It just goes straight to the server. I have found problems like this albeit with Qobuz. For example a new release last autumn which was shown as hi-rez 24/96. In fact the record company only provided track 1 as 24/96, all the rest on the album were MP3 supplied in error.
Still, here I am speculating which is against my own stricture yesterday. Hoisted by my own petard ( as we say) 
Sorry but is not as Anucp is saying . All the MQA streams , all , albums, playlist,songs ,has exactly the same problem: playing in Mosaic plays as MPEG in kbps and not more as before as MQA or MQA Studio. Because of that there is not icon MQA in the Bartok front display , because is playing something strange that is not MQA , is MPEG…that’s the big problem. And of course don’t sound as well as before when it was real MQA, very well played by the Bartok.
Same issue here. Went to Tidal last night and noticed this right away. The sound quality wasn’t there. I thought something was wrong with my Rossini. As of now issue continues. I tried 20 random MQA tracks and all the displayed MPEG and were 44 or 48k. I’m glad to know at least it isn’t my DAC. Hopefully dCS gets this sorted soon.
Clearly not all MQA tracks are affected, Lana Del Rey, right at the top of the new releases under Tidal Masters plays just fine. And others.
Today and now MQA is playing well again! Someone did a good and fast work to fix it, I don’t know if on the dCS support side or onTidal side, but is working well again , all the MQA albums tested works well and the MQA icon is come back in the Bartok display , and the SQ is again excelent!
Hypotheticals! is OK now but I found some others songs in MPEG yet…
Not all the MQA albums are OK now as I was saying before …
Is crazy…now Lana del Rey is MPEG again…
Actually that Lana Del Rey album is what I tested yesterday and was showing up as MPEG - you say it’s showing as MQA today? That is indeed a difference…
Sometimes is MQA now, but not always , sometimes is MPEG…
The issue started manifesting for me as well. While listening to an album, MQA would switch to MPEG randomly when starting tracks. Repeatedly restarting the same track from the queue would eventually kick it back into MQA mode.
Clearly a defect, whether it’s on Tidal or dCS’ end. Hope it gets fixed quickly, it’s very annoying.