That's one take.
Another is that the 2019 Corbyn led Labour got more votes than the 2024 Starmer led Labour, the massive difference was how few votes the Tories got this time around.
Labour 2019 10,269,000 Votes, 2024 9,705,000 votes
Tories 2019 13,966,000 Votes, 2024 6,827,000 Votes.
Now...