So I just got back from the Pong Nam Ron/Kamrieng border. Haven't been there since 2020 and there used to be loads of farangs doing the hop, but this time around I was the only one there. It looked like mainly Cambodians doing the crossing. Indeed, when it was my turn to get my passport stamped, the Thai immigration officer seemed surprised to see a non-Asian.
After taking my passport and looking through it, instead of scanning and stamping it, he called someone over to him from outside, a heavily tattooed man with no uniform, who I think was Cambodian. After saying something to him, he then handed the guy my passport, who in turn asked me if I wanted to use him to get my Cambodian visa, which would cost 2000 baht. I replied that I could go and do it myself, to which he replied that if I used him, I could come back to Thailand the same day, whereas if I did it by myself I would have to spend a night over the border until I was allowed to return the next morning.
I found this odd, as I had never heard of this before but I told the guy I'd take the risk. My passport was then handed back to the immigration officer, who scanned and stamped me out of the country.
The Cambodian visa actually cost me 1500 baht ($43) but on the visa it read that I had paid $30 for it, so it actually should have been around 1000 baht.
After stamping in and out of Cambodia, I then got back into Thailand with no issues whatsoever.
Moral of the story is, they try to rip you off on both sides of the border so I would advise changing money into dollars and taking 30USD with you if ever you take this visa run.
Happy travels.