Cat ears dirty or mites??

I’ve had my cat for 3 years and did mites treatment for a while for suspected mites, he’s always had this and has been to the vet when we got him and they didn’t say anything about mites. He’s strictly indoor. any ideas?? or is it just ear wax

Hello - from here, using my mobile screen to view, there is little to see and if you told me that this was your cats' normal then I might beleive you.   However, something is concerning you and you can see this ear better than I can.  Suggestions may be, "normal for them", or local allergy reaction (ears are essentially skin in an elaborate hole and if the skin is going to react, it tends to choose the ears).   Mites are possible, but usually a few mites live in the ears all the time and move in on a larger scale eg when the immune system is down.   Please be guided by you vet on this one and avoid putting treatments down the ears unnecessarily, until any problem can be diagnosed.