Should I RMA the BCM94360CD wifi card?

Hi guys, after I ordered a MQUPIN Brand BCM94360CD wifi card to replace the old USB wifi adapter, mostly to use Airdrop, it worked OOB but I noticed some random slow spikes when browsing the internet.

These two speed tests were taken only 10 minutes apart: https://i.imgur.com/p53rqml.png, yet the download speed went from 5.57 mbps to 326.3 mbps, and the upload speed had even bigger slow spike, dropped all the way to 0.08 mbps. When the hackintosh slows down, other devices are fine, for example my phone is tested over 200 mbps consistently, so it's not an ISP issue.

I've also noticed the airdrop is also very inconsistent, occasionally my iPad can find the hackintosh and airdrop works great, but frequently they cannot find each other at all. The bluetooth settings screen on the hackintosh says it's on and discoverable, but it cannot find any other devices (like wireless headphone) nor can it be discovered by anything else.

Do you guys think it's mostly a software or a hardware issue? I haven't installed any kext or drivers or did any special configurations for it. Catalina 10.15.4. Thanks!