Apologies from atommann (an engineer from JLCPCB), about Gerber X2 files at JLCPCB

[DavidR]

@Naib

If you look at the test it would appear the issue is with appature and not X2 ( in as far as an exhaustive combination test was not performed). This makes more sense as X2 adds info to COMMENTS and thus is ignored by older parsers
If X2 fails then there is a flaw in X1 readers as it is non-compliant

It seems there are issues with using X2 even without aperture macros - see my post here: JLCPCB - strange issue with rounded rectangle pads + kicad nightly - #6 by DavidR

I do agree though that in principle it should be fine for KiCad to default to using Gerber X2 because of the backwards compatible design. And as @atommann said, JLCPCB are working on a preprocessing script to strip out the X2 stuff which shouldn’t be too difficult to do.

On the other hand, I think the move towards using aperture macros is a bit more questionable. There was nothing wrong with the old approach, and it seems that multiple pieces of software struggle to implement aperture macros correctly (see Gerber Aperture Macros are hard for everyone | Horizon EDA Blog ). So, I think it may be wise to have aperture macros off by default.