When the chain is congested, the mempool is like a rush hour queue: clicking send doesn't mean the transaction is immediately on the chain, it just gets a number first. Miners/validators prefer to process transactions that pay higher tips first, so the same transaction might go through instantly for some and get stuck for half a day for others. If it stays stuck too long, it might get bumped out, or your subsequent transaction might be stuck because the previous one hasn't confirmed and can't move together. Usually, during congestion, I prefer to do less transactions; if I really need to, I keep an eye on the fees and avoid overpaying. Anyway, waiting a few more minutes is better than blindly increasing the fee. Recently, hardware wallets are out of stock again, and phishing links are everywhere. I no longer trust those "pop-up windows urging you to upgrade or sign quickly"; taking a little more time can save a lot of trouble.