I think output impedance issues are the reason for more bass. Truthear x Crinacle Zero doesn't work correctly unless a low output impedance amplifier is provided. This IEM has two drivers with a crossover, and the bass region of the spectrum has the higher impedance, so it uses less current relative to the highs at that volume level. Devices that struggle to provide enough current will thus tend to recess mids and highs. You have probably never heard how this IEM is supposed to sound.

Cheapest thing that should drive them just fine is the $9 Apple dongle, as its output impedance is less than 1 ohm. One known issue is that Android phones can't adjust the hardware volume of this dongle, so maximum may be a little on the quiet side for some.

Edit: dug up the ASR measurement of the impedance: https://www.audiosciencereview.com/forum/index.php?attachments/truthear-x-crinacle-zero-iem-thd-impedance-measurement-png.230795/ which is smoothly variable but also rises towards the low end. 10 ohms is less than most planars, and planars usually also have constant impedance.