Yes - you can use an Apple USB-C supply to power your RPi4, but you will need to pay attention to one detail that I'll cover below. You need not worry about damaging your RPi from the higher voltages. These higher voltages are part of the specification for USB-C that all manufacturers are supposed to meet. The "major error in manufacturing" that you heard of is a fact, but this was due to a failure by the Raspberry Pi design team - it had nothing to do with Apple.
The "One Detail":
With respect to the one detail I mentioned above, here's what you need to know:
If you have one of the early RPi4 units affected by the design flaw, you must use a
NON e-marked USB-C cable. Here is a verified list of
NON e-marked USB-C cables that you may find useful if you have one of the early, non-compliant RPi4 units. Here's one way to check if your RPi4 is one of the early (non-compliant) units:
$ cat /proc/cpuinfo | grep Revision
If the result is
Revision : b03111, it's an ORIGINAL RPi4 with the USB-C design flaw.
If you have one of the later RPI4 units, know that The Raspberry Pi Organization has since corrected their faulty USB-C design, and you may safely use any compliant USB-C cable with it.
If you're interested in further details, there are other Q&A here on RPi SE relevant to your question - here's one.
Other Potential Power Issues:
Your question suggests you maintain several RPis, so I'll add this:
Since the defective RPi4 design was corrected, it seems the most common issue is with low voltage delivered to the RPi4's USB-C connector. This is due to two factors:
RPi4 requires more power than previous RPis due to performance enhancements.
Physics: more power
--> more current
--> more voltage drop in cabling.
For the RPi4, the only solutions are "better" (higher quality) cables with larger gage wiring to carry the 5V power, and/or shorter cables. Extrapolating to future generations of RPi, it seems likely that input voltage may be increased from its present 5VDC to 20VDC - currently the upper limit of the USB-C specification.