OSR in shambles
In all seriousness, this shouldn't be a surprise. The GOP offers absolutely nothing to voters under 40 unless they're extremely religious or extremely wealthy.
Actual election data from 2008-2020 shows they undeniably have though or even 2012-2020.
Also the Gen X numbers don't seem right given Reagan did better with them than he did nationally in 1984 and Bush did around the same
Almost none of Gen X could vote in 1984. Gen X was born roughly 1964 to 1981 (not sure of the exact definitions FT is using) so the "twenty-year-old" numbers are averaging data from around 1984 to 2001.
About half of millennials couldn't vote in 2008 either, and many couldn't vote in 2012.