One of the first tell-tale signs of a flippening is the increase in ICO’s/IEOs. In 2018 we had a giant ‘ICO bubble’ and projects were being funded left and right. The price of gas skyrocketed and fees of hundreds of dollars or even thousands to ensure that you got your tokens on the ICO were not unheard of.
Because Ethereum was used to fund these projects, the market cap of Ethereum rose exponentially. We have started to see the same increase now in 2021 with the explosion of dApps and altcoins being “born” on the Ethereum network.