Crypto ads are highly restricted / not allowed in Google Ads (exceptions may be licensed crypto exchanges which have specific approval by Google Ads to run ads). Most of the crypto ads in Google Ads are running cloaked campaigns.
Keep this in mind and then read below :-
run such ads using completely irrelevant safe pages
The only way to run such highly restricted / not allowed crypto ads in Google Ads, is to use safe pages which are completely irrelevant to the crypto niche.
So, you need to do your research about what cloaking is (in relation to Google Ads).
if they just used relevant safe pages
If they use relevant safe pages (relevant to crypto), then obviously, such ads (crypto ads) would not get approved and most probably Google Ads account(s) will get suspended.
We are talking about using a cloaker and running a cloaked campaign in Google Ads. This has already been discussed a lot in various threads in the https://www.blackhatworld.com/forums/google-ads.83/. Also Google "what does it mean to cloak a campaign in google ads". So, you need to do your research about what cloaking is (in relation to Google Ads).
Cloaking is done to to hide the main offer's landing page (money page) from bots and moderators. So, bots and moderators see the safe page and the remaining traffic (visitors), go to the main offer's landing page (money page). A cloaker filters the traffic accordingly, based on certain parameters.
Imagine you own an unlicensed bar in your city. In that case, on the outside, you will have your setup to look like a restaurant (this is like a safe page in Google Ads). Right next to your restaurant, you have a secret door leading to the bar (this is like a money page in Google Ads). When visitors come, your security guards will filter the visitors (traffic) and accordingly send visitors (traffic) to either the restaurant (safe page) OR to the bar (money page).
So, if you make your setup to look like a bar and not like a restaurant, then you can expect to get caught very soon, because your's is an unlicensed bar. I hope this gives you clarity about a cloaker, cloaking, safe page and money page (in reference to Google Ads).