Well, the reason it shows "low contrast" on the page, is because the purpose of the page is to illustrate the low contrast problem. There are many sections that show the contrasting example of good contrast. What you're doing is running two virus scanners, and the second one finds the quarantine folder of the first one. You then claim the first antivirus is a virus. Nope.
This was not a website designed for mobile - that's why it doesn't look appropriate on mobile. Not every website is designed for mobile - in fact there are usually two completely different websites for mobile and desktop. This one is only for desktop. This complaint is like renting a sports car and complaining it's not doing a good job at transporting your piano.
There is one actually valid issue with the website though, which you do not bring up. It singles out websites for some reason, when the issue has zero to do with websites. Windows itself - all over the place - has ridiculous light gray on white, or light gray on dark gray (in dark theme). It's literally not readable half the time. Android has the same - now with more empty space, and page scrolling through 2 lines of tiny text and a toggle that changes description on toggle, so you don't know what it's doing. Heck, the service tag printed on the bottom of my silver dell laptop, is gray.
then we have things like expensive custom license plates with nature pictures and a tiny font. that all the drug dealers buy. and lastly - faces. the only way to tell a nose from a cheek from afar, is light-tan vs dark-tan (in the shadow). And with some people, the only way you can find them at night at all, is if they smile at your joke.