In 2011 the Coalition government at the request of the Lib Dems gave us a referendum on abandoning the first past the post voting system. Recognising the fact that many voters support the idea of single member constituencies where the MP has to provide a good service to retain support they offered the country the Alternative Vote system. This is a cheaper and easier version of the French two round system. It is designed to ensure every elected MP has the support of more than half the voters.
Under AV like the French system if a candidate attracts more than 50% first preference votes they are elected. If they dont then the second preferences of candidates attracting few votes are allocated until someone does achieve 50%. So if this system had applied this time there would probably have been more Conservative or Reform MPs on reallocations.
This was decisively rejected with 68% voting against. England was more strongly against but all four parts of the Union voted No.
Reform now campaign for PR. PR systems often break the link between an MP and a single constituency, or creates  two classes of MPs. Some  can be elected locally and others are chosen as top up MPs from a party list. The U.K. system of electing MEPs was a list system. It meant many MEPs were casual over regional constituency correspondence, often redirecting to U.K. MPs who needed to take constituents issues seriously. An MP/ candidate who is top of his or her party list knows they will get a seat so there is no pressure to listen or serve well.
Labour of course need to remember that their large majority is based on only a third of those voting wanting them in government. They should also worry that so few voted. A heavily distorted Parliament relative to public wishes is a concern but there is no obvious voting model that is better or would be supported in a referendum.
No government should change the voting system without a referendum
We should be reluctant to abolish single MP accountability to a local area.
EU countries with PR end up with coalition governments. Coalitions often  take a long time to create. They start by the parties in the coalition dumping many of their Manifesto promises to electors to find a common platform with other parties they disagree with.
How is that better?
The Netherlands decisively threw out their old government. It took seven months to form a new one out of four parties. . They had to chose a civil servant as PM as they couldn’t agree to support the leader of the largest party to be PM.
If the U.K. this time had wanted a Reform or Conservative government it could have voted for one in sufficient numbers to secure it.