Lee Anderson had the whip withdrawn and that should have led to a recall and by-election. Instead, he has resigned from the Conservatives and defected to Reform in order to remain an MP. This is game-playing the system.
Whether we like it or not people tend to vote for the candidate of the party they support. The electorate of Ashfield voted Conservative, not Reform. Anderson just happened to be Conservative (at the time), so hopefully the electorate will vote Conservative again and get rid of Anderson.