So long story short I received an ESTA in 2018.
In early august 2019 People who have visited North Korea were no longer eligible for the VWP. I went to NK for a week as a tourist in 2015.
I had no idea about this, I was not asked questions about about travel history to North Korea (on my ESTA application in 2018, or at the border when I visited the us late August 2019 - a few weeks after the rule came in).
I’ve just gone to get a new ESTA, and have seen that North Korea is now on the list of bad countries. Which means I need a B2 visa.
I never break immigration rules on purpose so I’m gonna get a visa, I’m not going to lie.
But how screwed am I for that earlier trip to the us?
I had never been asked about travel to NK, I never lied to anyone or on any form, and the rules changed, unknown to me, 3 weeks before I travelled on the ESTA / vwp.