And by doing “Inspect” you still see the Main page Html … Well, i’m a beginner so i don’t really find an answer for you ^^‘. Exept by not going on the good page or opening an already existing code source page …
Try closing and opening your internet page, if it’s still doing the same thing, try on other page, other site, etc. Also, try to remember if you have installed something before this bug.
If it didn’t change, i really don’t know :/