In fact, some economists continued to argue after 2000 that “bubble” is a meaningless category. Uh oh. "Stocks have reached a permanently high plateau" - Irving Fisher, economist, early October 1929.
There is something different this time. People en masse have started using the S&P 500 and other index funds as a long term store of value. Large amounts of money buy these stocks every pay period with zero regard to performance or current market conditions. As far as I'm aware, this has never happened before. We don't know how this experiment will change the market long term or whether it will eventually collapse.
The 2008 crisis taught the US Federal Reserve how to respond to an economic crisis effectively, and they've been pretty successful at managing the current one. Note that Fed's main concerns are macroeconomic, so their assistance necessarily goes mostly to larger corporations and financial institutions, which seem to be doing OK (smaller businesses are suffering, but Congress stepped in for them... somewhat). I don't anticipate a liquidity shortage-triggered panic + recession like 2008.
However, all asset prices seem to be inflated. Real estate, crypto, stocks... all going up and up. They can't do so forever, it will be interesting to see how it fails this time.