Yup and a significant portion of those ads are definatly not school appropriate... From the mobile game ads that show a mostly naked lady, alcohol, soft-porn (chatbot type stuff), jump scares and whatever other crap google exempts from their "guidelines" for a quick buck.
The only (official) way to have all kid firendly ads is to use YouTube Kids, which also blocks all the usefull educational videos for anyone older than 4.