[GNU Make 4.2.1] Implicit rule not used

[Jari Vetoniemi]

Hi,

I have Makefile where implict rule is not used for target that is
prerequisite of another target.

You can see the Makefile here:
https://ptpb.pw/WxM9

If I remove the recipe from vitaserve target GNU/Make will not use the
implicit rule '%: %.c' for the target.
Is this a bug in GNU/Make or am I understanding the implicit rule
search algorithm wrong?