I honestly don't feel the De-Fi season, but if it really has happened, I don't think it's bigger than the altcoins season because altcoins season in 2017 was really huge, it made bitcoin's dominance to dropped, but now bitcoin's dominant is really stable and has increased to 68% compared to 35% + during the 2017 altcoins season.
This would be a good time to sell altcoins if you own any. The recent rise in bitcon price also drove the altcoins upwards but didnt quite sustain their price. Very soon they will drop before bitcoin if bitcoin fails to maintain this pumped price and tanks.
Because a rise of this magnitude is difficult to keep on. Selling pressure builds up and sell orders will go thorough because some fools did buy at 20k in 2017 and they were waiting for this rise in price.
Hence the craze of DeFi currently stopped a bit as people changed focus on bitcoin for now. You can get this idea also from the decrease in the forum threads about DeFi and increase in bitcoin price conspiracy theories/bullshit everywhere. Trust me, nobody really know why the price rose, all speculating. But it cooks up nice profits in leverage trading.