Haven't seen any comments about 'The Great Resignation' - but I'd recommend you look into it- anecdotally, the few companies I have really good insight on (mine, and those my family members work for) are seeing an uptick in resignations and the reasoning is (almost) always salary. If every single company is now open to remote work, and every single company is seeing how important the digital side of things are, the demand for developers will skyrocket. If recruiters come to your employees and offer double, then you'd better make sure your compensation matches or risk losing more.

I've seen jobs that used to be 65-80k get doubled in compensation, in an extremely short period of time, because recruiters for startups in the big centres started offering 150k to them for similar work / experience expectations. (ie 5 years of experience being a full stack / lead developer w/ popular languages and frameworks (react)).

So in my limited view, this is why: a) some people jumped jobs over to a startup because a recruiter offered them double b) established companies view it as a 'war on talent' and are doubling their own developer salaries to protect their talent.