Spent 2 years building my credit just to have closing an account drop my score almost 100 points

I’ve had a secured credit card for the last year and a half. Finally built my score up from 415 to 692, only 8 points away from 700. This was HUGE for me, I was so excited. I was offered a credit card through the same bank, Capital One, with a $4k like of credit. This was also huge for me because I’d never been approved for a credit card before, let alone for that limit.

So I thought, hey, why keep the secured card when I have an actual credit card through them now! I’ll just cancel my secured account and get that deposit back and switch to using my credit account. So I canceled it, then two days later I was notified that my score dropped 88 points. Literally the only update to my credit was that I closed an account. I wanted to cry. I’m almost back in the 500s. Why did this happen??? Is there anything I can do to fix it? Is it going to take another year to build back up to where I was prior to closing that account? This feels like a sick joke. It took one day to drop my score what it took one year to raise.