I think you are getting confused between Roon and TIDAL today (or at least yesterday), and “future TIDAL”.
TIDAL has just made available an extra non-MQA tier of subscription. It only seems to be launched in Australia right now. My guess it’ll come everywhere soon enough, but I am only guessing. This is brand new, and unless you are already paying less for TIDAL than you were last week, you are still on the “MQA” tier, regardless of what setting you pick in Roon.
As for me saying that you can turn off MQA streams in Roon, I made no such claim. The only claim I made was that if you turn off Core Decode in Roon and it’ll stop Core Decoding in Roon.
Switching to HiFi instead of Master only instructs us to tell TIDAL what to get. Tidal has been treating both as the same for many tracks, and in some cases, they even will deliver lossy AAC when you ask for Masters or HiFi. None of this is new, and none of this applies to the new 3-tiers of TIDAL subscriptions.
If you are trying to get non-MQA streams out of TIDAL, at the moment (unless you are in Australia), there is no way to do so reliably.
If you are in Australia, presumably you can switch to the new “middle” tier and get no MQA streams. I don’t have access to that new tier, so I can’t tell you for sure, and as far as I know, no one has reported information either way.
Once this is available to us, we (and others) will absolutely check on this.