I think the ranking is based on web searches.
The ranking could be misleading because some languages are harder than others. For example, Python has a different file layout style to other languages by having significantly important amounts of leading whitespace for delimiting codeblocks. Could it be that people search about the idiosyncrasies of a specific computer language because that language is alien to them?
Also, older computer languages (pre world-wide-web) have written manuals and books to describe the usage of the language. Perhaps, these developers sill access this written material on their desks so no internet search is needed ? For example, Programming the Z80 by Zodney Zaks circa 1979.
Think about how bad programming language would appear in the rankings ? I think a bad language would be highly ranked due to the difficulty in using the language.
I think Perl is easier to grasp than Python. Perhaps that is why Perl is ranked lowly as it is too easy to use?
There are multiple variants of C from K & R, ANSI C (C89) up to C23. I wonder which variant is the most popular ? But I think this ranking scheme will misidentify the most popular (mostly used) variant of C.