German here, I started with a mishmash of accents I think but it probably trended towards US-American. Then I binge-watched Monty Python and Doctor Who in my 20s and I can say with a fair amount of certainty that that’s the point where I inadvertently started doing a rather posh British RP accent. It shifts around a bit, depending on what I recently watched (David Tennant always infects me with his accent) but I find that stereotypical British accents are closer to what my mouth does in German so it’s actually easier for me than other variants of English. Now if only I could get rid of all the US-American vocabulary I’ve picked up over the years.