Many people think that once they click swap, it’s "on the chain," but in reality, it just goes to the mempool to queue up as a small transparent node. During congestion, your transaction will be pushed to the back by a bunch of transactions with higher gas fees. While waiting, slippage starts to act up: the price has already been pushed past you by others, but you're still stuck in line, and in the end, it’s either reverted or executed with a terrible fill. What’s even more frustrating is that some routing methods keep retrying or switching pools, looking like they’re “busy,” but actually they’re slowly pocketing the failed transaction costs.

By the way, recent NFT royalty disputes are also essentially a tug-of-war between liquidity and commissions; whoever can pay the "toll" on-chain gets to be executed first, while those who can’t pay end up queuing, failing, or being forced to accept worse prices. Anyway, when I’m congested now, I’d rather do fewer trades than spend half a day analyzing and realize with just two words: I was too impatient.