But now that I have the same issue on a completely different architecture with different kernel version it seems to indicate that this is not necessarily the case...
I think it all comes down to Linux kernel version eventually.
If you refer to this link, people are complaining the same macvlan issue on the 5.4.x kernel.
The reason it worked on 4.19.102-v7l+ with rpi-update is that they back-ported the patch on kernel 4.19.x.
So if you can find a way to update your arm64 kernel to 5.4.14, that should fix the issue.