Recently, people keep asking me: why is on-chain data sometimes available and sometimes not, like a subway gate blocking entry.

To be clear, what you're seeing isn't the "chain" itself, but the indexer/Subgraph/RPC relay station queuing.
The indexer first breaks down the blocks and records transactions, then the Subgraph creates queryable tables based on your rules;
if any step in tracking blocks is slow or if reorganization and rollback happen, the frontend is like a navigation suddenly rerouting: it first shows you the old results.
Plus, with RPC rate limiting, everyone is squeezing through the same gate, so you'll see requests suddenly timeout or balances/trade records "pause" for a moment.
Sometimes it's not your network issue at all, but someone behind the scenes flooding the API, like a traffic accident scene.
By the way, the recent NFT royalty disputes are also quite similar: you might think it's "market consensus," but often it's data delays plus display standards that stir up emotions, and creators only get more annoyed when they can't see the bills.
Anyway, when I look at on-chain data now, I wait for two confirmations before trusting it, and try not to get too caught up with the refresh button.