My battery backup is ok in asus max pro m2 (android 10 beta).
For the slow charging problem please calibration you battery or try changing the data cable. For calibration use you phone until battery reach 0 and phone shut down automatically. Then charge your phone till 100% in the switch off condition ( note the led will stop glowing after 100% charge). Unplugged the micro USB then switch it on keep the phone in idle for few minutes and then you can find the battery improvement and the slow charging will be fixed. If this method doesn't work then change your data cable or try to use power bank for charging.