When you withdraw a J1 US visa application, is it considered as a refused visa?
If not, should I still mention it in my future US visa applications?
I contacted IEP who I used for my J1 Visa. They deal with thousands of J1 visas a year, and confirmed that:
Hi, no it wouldn’t be considered refused if they cancelled it.
Given they have students and others applying and changing degrees and getting jobs and more, I guarantee that they've dealt with it before (I used them 14 years ago), so they're a good authority on the matter.
As it's not a refusal, you won't need to declare it in any future applications, unless SPECIFICALLY asked about, obviously - don't lie if a border agent asks if you've ever applied for one in the past.