They are making him more unelectable by all of the infighting.
Starmer is very unpopular but tbh, any leader from any party would be unpopular right now because the country is in such a mess. And that mess most certainly isn't all of Starmer's making, even if he has helped to contribute to it.
They need to stop the political infighting, unite as a party and focus relentlessly on delivery for the country. People will start to feel more positive towards Labour if and when they perceive that life is getting better for them - a new leader is not going to make the difference.
Starmer seems to lack vision, so he needs to bring together other talents from across the party to help him find that vision. It doesn't necessarily have to come from him, but as a government, they do need a clear and radical plan.
They also need to tell a much better story about what they're doing. Starmer himself might not be the best person to tell that story, but I don't think that matters if they get the wider comms right.
We don't need a revolving door of PMs right now. If they elect a new leader, the infighting will all just start again in any case, and the new leader will still face all of the challenges that have faced Starmer.
They don't need to change leader. They need to do a better job of running the country.