$GAS This is called a chart created by the exchange.

When the market is dropping, many people go short, so the exchange pushes it up to catch them.

Then it comes back down to pick up longs, as the Altcoin market is dropping, how can these low-cap coins have a strong increase?

These low-cap coins are very misleading, don't have too much hope, whether going long or short, it's easy to get liquidated.