When the mempool is congested, your transaction is basically waiting in line like riding the subway: first shoved into the pool to sit there, miners/validators glance at the fee, and if it's too low, they just ignore it. Then various routers and packers start "picking vegetables," conveniently taking the arbitrage opportunities (don't ask, just MEV in action). If you happen to get stuck in the middle, you might wait for a long time, get dropped, or even if someone else does the same operation first, when you try to get on, all that's left are slippage and failure fees.

Recently, there have been a lot of guesses about testnet points and whether the mainnet will issue tokens... The congestion becomes even more obvious: everyone rushes together, and on-chain it’s like a cafeteria opening for meals, only recognizing the fast and those willing to pay more. To put it simply, don’t believe in the narrative that "once I submit, it will definitely be executed"—it's only probabilistic: pay enough fee + don’t try to squeeze in with the crowd at the same second, and your success rate increases a bit; otherwise, just consider it paying tuition to the chain, for now.