Why would you think that volume was fake back then but less now? Back then exchanges were overloaded with people in a rush to buy Bitcoin and cryptocurrency. Today, there's almost no interest in Bitcoin or cryptocurrency.
Exchange web traffic is also way lower, according to Alexa. Binance was in top 200 sites worldwide in late 2017. Today it is far lower:
It was also only a few months ago that Bitwise report concluded volume on CMC was 95% fake.
That report came out 7 months ago and that is actually part of the reason I believe it is harder now. CMC acknowledged the report and has beefed up it's reporting protocols. They even have a metric on their page now that says sort by reported vs adjusted volume. Not only that, but exchanges are looked at much more closely now then they were 2-3 years ago and it's more difficult to pull off shady practices then it was then just in general.
Traffic metrics could mean several things. For one, it likely mostly just applies to retail. The CME futures are much more robust then they were back then, by orders of magnitude. That volume likely came from somewhere and is much more likely to be institutional. Plus you have Bakkt and a couple other institutional side investment products/platforms showing increasing activity. It's very possible you could have a drop in retail interest and an increase in institutional interest that more than makes up the difference, and you likely wouldn't see that at the popular crypto exchanges.
Regarding google trends, again that is likely showing a drop of retail interest plus there is always the fact that once you search for something like bitcoin to understand what it is, there is less of a need to search for it again. Bitcoin is more well known now than at any point prior. It's on CNBC every single day and has been mentioned by the president, the treasury secretary, and the FED Chair all in the past several months.
There is no way of knowing for sure that the volume is 'more legit' now than say 2-3 years ago, but intuitively it seems very likely that it would be citing some of the reasons mentioned above.