You’re right in your thought. It should be quelles not quels because erreur is a feminine word.
It would appear to me that the first item in your screenshot is incorrect.

In fact, opening that link shows the correct form (i.e. quelles). This leads me to believe that there might have been an indexing error somewhere in the process.

You seem to know rule, that is that the interrogative adjective quel agrees in gender and number with the noun it modifies.

Quelles sont les erreurs à ne pas commettre. (fem. plu.)

Quels sont les différents types d’erreurs à ne pas commettre. (mas. plur)

Apart from the fact that we can find lots of incorrect sentences on the Internet (and this in all languages) it seems your images show a mere google search and you have not followed the actual links.*

If you follow the link of the first one “quels sont les erreurs à ne pas commettre” you can see there are in fact no hits on the page because the words appear separately on linguee.

The second image has a correct sentence, types being masculine and plural.

*_{I have actually found one result (not the one you chose!) with quels sont les erreurs on the Internet. It is a mistake and unless we are sure we are on a trustworthy website everything we read on the internet has to be doublechecked.}