Here you are wrong. If you download the driver from D-Link D-Link Technical Support, you'll see that the adapter uses the very common Realtek RTL8156 chipset. Currently RouterOS only has driver for this chipset on the x86 platform, since 7.16:
and not yet for your hAP ax³ which is ARM64. All the USB adapters that use the chipsets from Realtek share the same kernel module r8152 which is already bundled with RouterOS. The problem is that the module from the pretty old kernel version 5.6.3 (which RouterOS still uses) does not even supports all revisions of the 1GbE RTL8153 chipset, and has no support for the 2.5GbE RTL8156, for which you either need to backport from at least kernel 5.13 or compile from the source code provided by Realtek:
And apparently this is currently only done for x86. If MikroTik has not mentioned "ARM64 - added RTL8156 driver support" in their changelog then you can assume that there is no magical support for your router yet.
That your hAP ax³ sees the adapter with some broken properties is solely due the fact that the chipsets from Realtek have some shared basis for interfacing with the kernel (and in the most recent kernel the up-to-date version of the r8152 kernel module is used for all of them), but it is clear that the ancient r8152 module from 5.6.3 has no knowledge of any new or change stuffs that come with the RTL8156 chipset.