I live in a country where there is PR, and I can assure you that it's no panacea. I say this because I see the 'if only we had PR it would all be fine' come up a lot.
The issue in the UK is declining quality of political debate and declining capability and integrity of people in government because of gullible voters. This is way bigger than Brexit. The same rogues would all be around in a PR system. The only difference I can think of is that Nigel Farage would be in cabinet as part of a Tory-Brexit coalition.
When you have people like Johnson, or Truss, or Raab, or Gove etc running the show, and you have people like the Labour front bench of the last half decade opposing them the outcomes won't be great whatever the electoral system.
Over a decade ago I was talking with my mother, who still lives in the UK, about a conversation she'd had with her hairdresser. How are you voting in the mayoral election, she asked? The reply: Oh, Boris. He's a laugh.
That's the issue. If politicians get voted in because they're a laugh, or because you believe then when they promise the moon, you will find yourself governed by idiots regardless of the voting system.
When people say they can't see Starmer as PM because he's 'boring' I feel like headbutting the table. Politics aside, he's just the sort of person you want in charge, serious, successful career, intelligent, not a utopian and not a bullshitter.