Hi
The "Unlock Grid" option is still there on the original PC version.
You say you play on both iPhone 11 & iPad Pro, where it's not available. You also say that when you play on the PC you do so via Bluestacks. I assume this is to emulate the mobile game (otherwise what's the point?). This means you are playing the mobile game on the PC as well. The "unlock grid" option is only available on the PC version, played on the PC, and not via an emulator.
I hope this makes sense, I don't personally play the mobile version, but that is what I take the previous replys to mean.
Cheers!
Rich