Are you sure Linux has "so many fewer" vulnerabilities, can you show some data? The CVE list for 2021 does not seem to support this claim:

https://www.cvedetails.com/top-50-products.php?year=2021

I'm sure there are many ways to slice this data, and in some metrics Linux might win. But apparently "so many fewer" claim is another old myth - it many metrics Linux has so many more of them.