There are lots of projects launching these days and of such as DeFi projects, which seems to be the most common and that is why it could to be attributed to Defi. However, I do not agree that it is mainly on Dedi projects, but on DEXes.
Most platforms that are DEX-like are the main cause of the high gas fee. Using them for travsctkns, most especially in situations where there is gas front-running, it tends to cause more increased gas fee on the network.