YouTube sponsor segments are not subtle “place a Coke can facing the camera” integrations. They are dedicated ad segments with scripted (typically by the advertiser) promotions, often entirely unrelated to the video or channel.

To the end user they are indistinguishable from other video ads on the platform except the ad read is often (not always) done by the creator.

I don’t have hard data on the ratio but it’s not uncommon for a 10 minute video to have 1-2 minutes of full-interrupt ad segments embedded in the video.