There's long been huge dissatisfaction in the ranks of Tory MP's, and those Tory MP's are hearing it load and clear in the constituency parties - Johnson isn't up to the job, many of his cabinet are pretty useless, and - unlike Corbyn - Starmer is a formidable opponent.
It's not if, it's when. The Tory press say the same things.
They would like him to see the writing on the wall and retire gracefully having 'acheived' Brexit and then been mortally wounded in the fight against covid, leaving them to find a new leader/PM who can a) run a country, and b) win against Starmer.
As ever however, if he won't do the decent thing they will eventually do it for him.
(Interestingly, Geoffrey Clifton-Brown, treasurer of the 1922 committee, was on times radio in the last week openly talking about this being Johnson's last chance to get a grip and include his MP's. He didn't say 'or else', but his meaning was crystal clear, and he didn't contradict John Peinaar when the latter started suggesting those letters to the chair of the '22).
This stuff about an 80 seat majority and therefore being invunerable fails to understand both the party and parliament - Johnson is PM because Tory MP's say he is. He wasn't popular among MP's to start with, his constituency has always been outside parliament (and the party?), and his performances over Covid and against Starmer have been woeful, and they want him out. He can either take the watch, the whisky and the fake smiles, or he can take the bullet - the first is preferable, the second would be messy and painful for the PCP, but they've done it before, and each time it gets easier....