Tidal HiFi really lossless?

You have to set it correctly. On the phone, there's a streamer quality setting, same for the PC app.  Not sure about OS X.

Tidal is lossless but I've never gotten up to 1411 kbps streaming Redbook. It typically sits in the 7-1000 kbps range even on Wifi in my home. Sounds great though.

Once you select “high quality” for your streaming quality, you’ll get lossless playback. It streams to you in a compressed format so you’ll never see 1,411 kbps over the internet but your device is converting it to 16-bit/44.1kHz/1,411 kbps and sends that to the DAC chip.