It can also depends on the browser you use and also on the addons you may have installed on that browser.
Lately, I have seen people, friends of mine rather using dedicated apps to watch videos on Youtube without ads interrupting their videos, perhaps you are also interested on that. There is Free Youtube and Newpipe, for example, though, I think that if the gambling nature of the advertisements is the problem, it would be enough just to switch off your preferences, as I showed you earlier.
I read from several people that there are lots of free ways to avoid gambling ads by means of special applications or cryptic browser methods.
Normal people like me will never subscribe to youtube premium, why do we spend money on Youtube premium only to avoid gambling ads ?
By the way, even if you somehow do not see the gambling ads, there may be other ads that will be shown to you by youtube. So in any case, unless you have paid and opted for the youtube premium, you will have to watch the youtube ads.
Anyways if the gambling sites are paying youtube to display their ads, we have to cope with it because this is another form of marketing by the casino's.