My iPad charging situation is very hard!

I have this iPad 4 since almost 2015. It has face a lot of problems with charging and a new one is here!!

Sometimes it shows that the “accessory may not be supported “ or it does not charge unless I put it on a certain angle. I changed the cable and the charger, I cleaned the charging port and nothing happened !

after buying a new usb cable it started charging

but again, it started to show the “not charging” thing again but in fact it charges despite the fact that it’s showing that it's not charging

but the charging is EXTREMELY SLOW, the voltage and the energy of the charger and the cable are just perfect to the ipad needs but it barely charges 1% in an hour !!!

I’m really confused and I need advice please???