Are these 3 pins connected in the schematic?
If no then kicad will rightly not allow them to be connected in pcb_new.
If they are then check your drc settings and also the settings under the dimension dialog.
Maybe also use the highlight net tool to check if pcb_new thinks these pads should be connected.
If not all 3 pins get highlighed at once with this tool then your pcb and schematic might be out of sync. You need to export the netlist from eeschema and import it into pcb_new everytime you make a change in the schematic.
If you want the zone to connect to them then remember that zones have their own clearance and minimum width settings.
The resolution is low, but it appears pads 1,2,3 are on different nets, so they should not be connected.(For a MOSFET it seems unlikely you would connect those 3 pins). I can’t explain why there is an air-wire there, maybe a bug/graphic artifact.
The schematic shows what should be connected, which you can see but we can’t…
There are a lot of things you could do. Following the advice of @Rene_Poschl is the smartest of those things. He helps maintain the libraries so this is his area of expertise in the Kicad world. Saving this off in your own personal library so it doesn’t get changed in the future is the first step. You rename it so it doesn’t conflict. Change what you want after that.