Why would you ever need to _advertise_ a cryptocurrency anyway? Can you imagine someone advertising a specific stock, or a fiat currency? That'd be ridiculous! Seems likely to me that most of those ads are just trying to prop-up the price of the currency they're advertising so that the one who bought the ad can dump their holdings at a higher price.
I'm a little concerned though that Google's ban here seems to go beyond just ads for currencies themselves. For example, is Brave no longer allowed to advertise its browser on Google because there's a cryto coin associated with it? Are exchanges or hardware wallet manufacturers like TREZOR no longer allowed to advertise their services? If so, I think these restrictions might be overly broad.