Which ISP was doing this? It's worth calling out the bad actors.
It's pretty much most Indian ISPs and in this case it was ACT Fibernet.
Wouldn't the list of ISPs not doing this be easier to make?
No.
There's a difference between what you're likely referring to, where the ISP's own DNS, which most people are using by default, returning particular results, and what the author is showing here where the ISP is actively tampering with outside DNS responses to insert incorrect responses.
Until now, I was not aware of any ISP doing the latter.
Only one ISP I've used ever did this (VodafoneZiggo) and that was over a decade ago, and only to redirect domains that couldn't be found to ad-filled "search" pages.
It's not universal, the occurance or this type of abuse seems to vary wildly from country to country
Want to ISP-less in India? :D At least ACT doesn't blanet throttle/fail uplaods of any sort like Jio does on its 5G – even LLM calls fail.