Yep, I know that pronunciation difference - often spot it on American TV shows. But then, with “herbs”, Britons pronounce the “h”, whereas on American cooking shows, it’s always pronounced as 'erb - as it would be in French
On our earlier trips to America, it was quite often the case that our accents were not recognised as being English. I was regularly asked if I was from New Zealand or, from time to time, Scotland. Our accents are nothing like either. That’s not happened for some goodly number of years . I can only speculate but reckon that Americans probably now hear a wider range of accents on British TV programmes.
On the other hand, my friend Paul (who is a lawyer in Kentucky) has another friend living in my metro area. Paul can understand me (so long as I slow down my speech somewhat) but he really struggles to understand the other guy. It’s about accents - me from the south of the area and middle class and the other guy, working class from the north.