https://pine64.com/product/rockpr…oth-5-0-module/ says this is a Cypress (aka Broadcom) CYW43455 SDIO module so the fix is probably to use the correct firwmare/nvram files for the module. If there is no board specific file provided the kernel driver will look for default files and use them, but the current ones we package are sourced from some Amlogic boards and might not give great results.
Pine64 probably have the correct brcmfmac43455-sdio.bin/brcmfmac43455-sdio.txt files to use in distro images and you can override the ones we provide by creating /storage/.config/firmware/brcm/brcmfmac43455-sdio.(bin/txt) locally and rebooting.