I assume once they lose the whip they become independents, so their letter calling for the PMs resignation is discounted when they are counting the letters to decide when to act. This is what I read on Sky News about William Wragg MP.
‘Mr Wragg said he would not risk voting against Labour's proposed fracking ban as he did not want to lose the whip - and therefore invalidate his letter of no confidence in Ms Truss.
"I wish to maintain that letter," he told the Commons.
It is unclear when the letter was first lodged with Sir Graham Brady, chairman of the 1922 Committee of backbench MPs.
Conservative MPs are under no obligation to declare publicly that they have submitted a letter of no confidence in their leader.’.
I guess it depends now on how many MPs will be brave and stand up for their principles, which will risk the government but help their own reputations.