I've been watching the MEV/ordering issues these days, basically it's about the same transaction, whether it gets on the chain first doesn't necessarily follow the order you confirmed. Some people can "cut in line" to front-run, the most directly affected are ordinary token swaps and small contract transactions: larger slippage, worse transaction prices, and you might think you're slow, but actually it's the unfair queuing rules.

I'm also hesitant to be too reckless now, trying to split large orders, chase fewer hot topics, and set limit prices when possible (although on-chain isn't always perfect). By the way, hardware wallets are currently out of stock, and phishing links are everywhere... The more these situations happen, the more I feel that technical issues + security problems stack up. Beginners really can pay tuition just by being careless. First, understand your private keys and signatures clearly, then take it slow.