I personally think the advertising bump is why matlab is on there. Matlab programmers are the kind of dingleberries that love to pay for something that everyone else uses a foss alternative for.

The fact that the scratch language is in the top 20 should tell you how seriously you should take this metric. TIOBE measures the number of search hits mentioning the language. So a language that is popular with learners, or that has poor documentation and thus requires a lot of third party documentation, or that it is profitable to run ads next to will all be inflated.