19.07 switched 5ghz drivers. Have you tried reverting to the ath10k non -ct firmware and driver to see if it is better.
I replaced them on my bthub 5a to get mesh working, but while the -ct firmware was installed, I had also noticed some issues with my lg TV occasionally losing 5ghz connection when using a pre-release candidate version of 19.07. 19.07 BT Hub 5A: Mesh not working on 5ghz radio -> must load driver with rawmode=1 to add mesh interfaces
Uninstall ath10k-firmware-qca988x-ct and kmod-ath10k-ct and install the previous versions: ath10k-firmware-qca988x and kmod-ath10k.
Then reboot the router to get it to use the replaced firmware.