Why were my coins sold at a lower price than the Stop-Loss order I entered?

Hello. This thing happened a month ago, but I wanted to ask anyway.

On the morning of September 21, I opened a long trade at 18.900$ on Bitcoin. As I predicted, Bitcoin's price started to rise towards the time of the FED meeting. I'm not a person who uses Stop-Loss a lot, but since everyone I see said 'don't forget to use it', so just in case, I set a Stop-Loss order at 19.200$ while Bitcoin was around 19,450$. (On Binance btw)

After the interest rate was announced at the Fed meeting, as you know, within seconds, Bitcoin first went up to 20.000$ and then suddenly started to fall. My stop-Loss order didn't work at 19.200$ and it sold at 18.450$ and closed the position, almost the lowest point where Bitcoin fell.

In this case, I made a loss because of Stop-Loss. If Stop-Loss doesn't work on sudden drops, then why we should use it? If the order had never worked, I would still understand it. However, the fact that it worked at a level far below the Stop-Loss order I gave, that's a huge problem.

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