I believe there are two standards, “USB-A to USB-C” and “USB-C to USB-C” and often those plugs/wires aren’t fully cross compatible. I have no idea why this is the case or even if its completely accurate.
All of my usb USB rechargable lights work just fine on a variety of USB A and USB C chargers. Some lights (more expensive ones) 8nclided their own chargers. Granted, some do not work on C to C cables, but most do. I don’t have any Apple specific chargers, but modern charge protocols usually include the Apple 2.4 protocol in addition to the Huawei SC5 protocol, Samsung QC2.0 and 3.0, and some do PD as well. Not all charge at warp speed either. Older lights made before 2019 usually are limited to 1 A or 2 A max.
I’ve heard before that the standard is not as universal and foolproof as it ought to be. I think most people sing its praises because of the plug design alone (no more flipping it back and forth trying to make it fit) Here is an article about the USB C standard and the challenges it faces: https://www.androidauthority.com/state-of-usb-c-870996/
For what it’s worth, my experiences have been mostly positive. My android phone recognizes my iPad charger as “Turbo Power” charger and supports the 20 amps watts it delivers.
I don’t tend to use the charging circuits in my lights though.
So USBC to C chargers are smart devices, they can supply power based on the device connected to them. For getting that right, the connected device has to be PD compatible (power delivery standard).
Many of the cheaper USBC devices are not PD compliant, to save costs. So when they are connected to a USBC PD charger, the charger cannot determine what power should it supply to connected device, hence it will supply no power at all.
TLDR : they didn’t put pull-down resistors on the CC pins on the flashlight to tell that it’s the device and not the host, an A to C cable has these already on the C side (device), so it works even if they forgot the resistors.
If the flashlight has a Power Delivery chip then it will handle the resistors and work without issue and take advantage of the PD capability of the charger.
I have never had problems with USB-C flashlights. It just always worked.
To engineer this problem you need to:
Test different charging bricks with the same cable. If the flashlight is not charging, it might be the cable.
Then test different cables with the same charging brick: if the flashlight is not charging, it might be the charging brick.
Flashlights are not that common to have charging ports and new technologies (like you know, it is harder to find a phone without charging port than it is to find a flashlight) so it makes (some) sense it might not be as compatible with different cables and chargers as smartphones.
You can flip the plug around on USB C cables and that might works. I’ve had lights refuse to charge on USB C cables and flipping the plug around 180 degrees worked.
I only have one light with a USB-C port - it’s a little Rovyvon-clone keychain light. It works with all my USB-C chargers and power banks, old and new.
I think most flashlight manufacturers have figured it out almost 2 years ago. So I’m guessing these lights you’re talking about are near 2 years or older. So it’s time for some new lights.