I’d take most DNA ethnicity analysis with a pinch of salt. Mostly harmless entertainment, and about as accurate as a horoscope. It seems to assume that people never moved which is just nonsense. There has been so much internal migration around the British Isles in the past 4000 years as to make a DNA breakdown between Irish, Welsh, Scots, English etc pretty meaningless. Most of the population all share a common Brythonic origin ie they are descended from people who migrated north through France as the last ice age retreated. When they got to Britain they swarmed around everywhere. Some moved north to Scotland, some west to Wales. And many continued to move after that for military, economic and cultural reasons. Though southern England has been inhabited for 400,000 years, Ireland has only been inhabited for about 8000 years. Many of its early settlers came from Britain. Then many Irish moved to Scotland, notably around 495AD when the kingdom of Dalriada was established by the Scotiae tribe from Co. Antrim, who gave Scotland it’s name, and who ruled Scotland and part of Ulster. So Scotland is named after an invading Irish tribe who came in sufficiently large numbers to be able to rename the country and to introduce their own language, ie gaelic. In the 1600s, 100,000 Scots and a similar number of English and Welsh moved to Ireland as a part of the Plantation of Ireland and also because of a severe famine in Scotland in the late 1600s. From the 1800s they were moving back from Ireland to Britain in hundreds of thousands because the employment prospects were better there. Therefore the idea of the Irish and the Welsh, Scots & English being distinct ethnic groups for DNA purposes is just daft.
(DNA is good for lots of other aspects of ancestry though).