This is just partisan propaganda point. The median age among Republican registered voters is 52 and among Democratic registered voters its 49. Another way to look at is this, 56% of the Republican voter base is above the age of 50, while it’s 50% for Democrats. They’re both very old and the gap is substantially small. It’s not only the Republicans who are losing the younger generations. https://www.pewresearch.org/short-reads/2020/10/26/what-the-2020-electorate-looks-like-by-party-race-and-ethnicity-age-education-and-religion/