I wouldn't discount it, but I think many software devs continued working from home instead of getting laid off. maybe all those kernel contributors found themselves with an extra 2/3 hours in the day without the daily commute? Not to mention not being able to carry out daily social lives + leisure activities
There are a lot of us developers out there who have had less free time during the lockdown. Whether it’s because of having young kids or doing charitable work in the local community for those less fortunate.
How much of Linux development is actually volunteer work? I assumed the bulk of the work was done by professionals whose employers were paying them to work on the kernel.
In that case, I could see a non-trivial number of those developers being in a situation that their other work commitments were slowed down, so kernel development got a bigger chunk of their time.
Not a lot, you can see it on the development statistics that LWN releases for every major kernel releases, for 5.7, it's only about 13-14%, so most people working on the kernel do indeed get paid for it.