When the mempool is congested, I always feel like I'm waiting in line at the cafeteria: submitting a transaction is just like taking a number, and miners/block producers pick the "more appealing" ones first (in plain terms, those with higher fees paid more happily). So your transaction either slowly gets pushed back, or gets stuck in the middle and repeatedly reordered, or even expires/replaced, which isn't surprising. Recently, new L1/L2s are offering incentives to attract TVL, and suddenly there's a bunch of "mining, proposing, selling" back and forth on the chain, making the queue even messier... I stare at pending transactions in a daze, my eyes sore, my neck stiff, even though there's no significant movement, my stomach feels a bit tight. Anyway, now I take an extra two seconds before placing an order: if there's no rush, don't force it; if you're in a hurry, accept paying a bit more "priority fee," or you'll just be torturing yourself.