I suspect fraud. Millions of votes for Reform UK and only four seats?
Your suspicion is unfounded. The first past the post electoral system often results in such anomalies. What counts is the vote in each individual constituency, not your total vote across the country. It’s perfectly possible for a party to come second in every constituency, with many millions of votes, but thus fail to win a single parliamentary seat.
In the typical general election each seat is contested by six or seven candidates. So given that fact it's easy to see how the "Reform" Party got a noteworthy percentage of the national vote but only won four seats. Just think back to Ross Perot...20% of the popular vote,and not a single EV.