Unbalanced spacing in fractions

[Enivex]

Noto Sans Math

As you can see, the numerator is much further from the line than the denominator. For comparison:

Fira Math

[khaledhosny]

Are you testing display mode or inline? In display mode there is typically more space so that numerators in equations like \frac{1}{2} \frac{1y}{2} remain aligned:

Noto Sans Math:

Fira Math:

You can also check other math fonts.

[Enivex]

In display mode there is typically more space

I agree that that what Fira Math is doing is suboptimal, but in this case Noto Sans Math does seem to have quite a bit more asymmetric spacing than other fonts

From left to right: New Computer Modern Math -> Stix Two Math -> Noto Sans Math

This is indeed display mode, though the situation is also similar inline.

[khaledhosny]

It took a bit of fiddling since too many constants are at the play here, but I think the end result is better now.

Noto Sans Math with #76:

Computer Modern Math (TFM fonts):

Cambria Math:

STIX Two Math:

Fira Math:

[simoncozens]

Fira seems to shift stuff upwards when there's a descender in the numerator.

[khaledhosny]

Yes, but that is undesired, you want fraction in these cases to align. The new constants make the gabs above and below look balanced without breaking the alignment.