As you can see from the above image, this is no big deal whether one is set at default or not, you can change yours to what you prefer. This is why it's good to know what you are dealing with before dealing with it. Fine, this could be an agenda, and of course, it could be for money. Still, we can't verify that, and we can't teach anyone how to run their websites.
I don't trust any websites, so Coinmarketcap can't be an exception. But is their data useful to me, oh yes, especially this "Trending" feature. This feature helped me discovered $SOMI despite my busy schedule last week. You see, many people will continue to complain, while many others will benefits from what others supposedly called manipulation. This is a fast filtering feature for me, and I won't blame CMC if people do not DYOR after seeing data from them.
Everyone dealing with crypto should learn it first and know the possible propaganda that may happen, otherwise, do not involve in crypto. If you are experienced in crypto, you would know that to know the top and best performing coins/tokens, you need to consider the "Top" feature on CMC and trading volumes elsewhere on the website. "Trending" is not a feature to consider here, it's just a popularity, which lapses in a short time.