When you search for something, an ad on the same category will also appear. On social media sites or other places any random ad can appear including gambling even if we don't have an interest with them. If that can happen on them then why not in Google? but we can do something to stop these ads from appearing.
It's either we pay from a premium subscription or use an adblocker in our browsers. Google can't do much about them because they are also earning with it. In our browser settings there is also a feature called strict filters. This mainly works in explicit contents or something sexual but it might help to restrict gambling-related stuffs too.
We can only filter the types of ads we can do so that we don't see ads we don't want. And Google itself seems to need to filter these ads into the correct categories so that the ads appearing on the user's side match their search.
And that makes Google have to really go the extra mile so they can provide satisfactory service for their users. And those of us looking for the gambling games we want can also find them easily through a search, and maybe we can use more specific keywords to find them.