I have had experience of that in a different setting. In the 70s I worked in Ireland, in Dublin and out west, often only a few days at a time, so really more of a tourist. In the 80s and 90s, though I had several stints (of 9 to 12 months at a time) living and working in Dublin, mainly on the poorer North Side (think Mrs. Brown's Boys and you sort of have it). There was an undercurrent of anti-British feeling and there were some pubs which work colleagues strongly advised me to avoid, on account of my accent. In general I found I got on with most people I worked with over there, though there were a few who didn't like me because I was a "bloody Brit". At that time there were very, very few non-Irish people in Ireland
Fast forward to 2001, when I again spent an extended period living over there (about 10 months). This time there wasn't the constant staring if you walked into a shop or a pub and spoke with a British accent. There were, however, refugees. Many of them Bosnian muslims, but there were also a substantial number of Nigerians who all seemed to be employed as "doormen" on shops. British accents were very common in areas like Temple Bar at the weekends (thanks to Ryanair's cheap flights). Brits were (mainly) no longer the issue - it was the "bloody muslims coming here and complaining about adverts on the bus shelters" (the ones with bikini-clad women advertising everything from sun-soaked holidays to alcoholic drinks).
Throughout all of this I found the best defence was to study a bit of modern Irish history, so that when attacked (verbally), for being English, I had a modicum of facts at my disposal to dispute at least some of the claims and half truths. And the Irish love a good argument, so that generally smoothed the waters. Funny old world.
Amen to that
As a kid, our only holiday each year was a car drive to county Limerick to stay at my nan's very small farm. We would drive from Ealing to Swansea and then get the ferry to Cork, and drive up to the "farm". (late 70's to early 80's)
In those days no one gave a chite about that fact that of the 4 of us kids, my sister and I had "olive" skin. It just wasn't an issue.
With regret, I accept what you say about Dublin. I have only been there once, about 7 years ago, but yeah I did notice a shift in (some) people from you lot (Brits) deserve to be unpopular to a state of "you come here and spend money- now we don't like another group of people".
Back in Limerick county, I was surprised at how many members of staff in the local hotel were Polish when I last visited before covid, but I didn't hear anyone complain about them.