RPGMemes

Generally I've seen it rules that the overlap needs to cover >50% of the square to affect it. In which case you have the exact same coverage as before. But in this case I'd just rule that we shift the grid 45 degrees so it lines up again and move units to the closest square that aligns. I.e. don't use geometry to try to munchkin.

There's a bunch of grid-based shapes that pertain to the rules of 5e as well if you need that. Also 5e fun fact: a circle or radius affect is going to look like a square since diagonal distance is not accounted for, but in Pf2e it looks closer to an actual circle.