You are using the LTS-kernel, have you tried the mainline kernel? Or the zen-kernel?
Also are you using a gpu-switching tool? Like prime or envy-control? With some laptops that don’t have a physical switch or a setting for it in the bios that is needed.
About the wifi… There I have no idea, but I have seen some posts, some also recently, that mediatek chips sometimes cause issues on Linux. This one like here is older. But just an example.
I’m not sure what driver you would need, or if you have the correct one already installed but it may have a issue right now, maybe it’s gone with the next update, or maybe a different kernel could help.
Maybe someone else knows more