Google Ads label themselves as "advertisements" "ad choices" or just the icon to rotate the ads depending on ad type. So if the ad doesn't display, the label doesn't either.

I've always put enough space around the ads so not to confuse it with content. Never saw a need to manually label them again. Haven't had a problem in over 12 years of publishing Google's ads.

Thanks. I know this is ok for adsense but think perhaps the rules are more demanding for google adexchange?
Certainly the label on many adsense ads, including text ads, is very discrete, and I can see that most major news sites also add the 'Advertising' label above the ads to remove any chance of confusion.

Well I use Adx and Adsense, which is why I said Google Ads and not specifically Adsense.

Anyway, I don't see it interfering with the balancer.

The truth is it's gray area. Labeling it "too clearly" can trigger the rule excessive attention to ads. A couple years ago a rep told me to add the labels at a local event (I previously did not), then another rep told me to remove the label at another online support/review roughly 6 months after I added them. It was waste of my time.

I have since not used any labeling for all my sites, I follow these rules personally:

kept a good distance,
made sure the surrounding texts / images stand out from the ads. Ie I avoid color / layout blending
the language adjacent to the ads do not suggest the ads are "content".

Ad balance is a stand alone feature.