Just finished flashing and someone else is talking about cross-chain bridges "waiting for confirmation, what exactly are we waiting for," I also casually want to say a few words.

The thing about bridges is, frankly, translating the state from another chain; you either trust a group of people (multi-signature), or trust a set of data feeds (oracles), or trust both a little.
Multi-signature's biggest fear isn't "slowness," but that signing rights are too centralized, or that people are added or replaced temporarily without your notice;
oracles are about whether they say your funds have arrived, and you really get them. If there's a hiccup in the middle, the bridge can easily turn into a withdrawal machine.

So "waiting for confirmation" isn't esoteric; it's waiting for the result of that chain to be less susceptible to rollback/reorganization, especially during mainnet upgrades, hard forks, or node maintenance.
Ultimately, which fork is considered the official history is really a gamble.
Recently, everyone is guessing whether ecosystem projects will migrate, but I'm more concerned about whether the bridge is secretly adjusting parameters or changing thresholds during these time windows...
Anyway, my usual habit is to avoid cross-chain transfers before and after upgrades; if I really need to cross, I prefer to do it slowly, wait for several rounds of confirmation, to avoid waking up and finding myself "settled" on another chain.