An alternate source - https://www.youtube.com/watch?v=g70ncHcaBiE

Sri-Lanka is not self sustainable in food and energy it has to import stuff. You need USD dollars to do this...

Sri Lanka has a lot of debt, the payments for which are paid in USD.

Pandemic reduced exports and USD coming into the country, and the country runs out of USD.. (foreign reserves). It relies on tourism among other things...

If you have very little foreign reserves everyone needs to bid more local currency to make international transactions so their currency collapses against other currencies - they need to prioritize for critical imports now

Even if their local central bank didn't print their domestic currency this kind of currency collapse would have happened. Its because of their government they took one too much debt and couldn't balance outflows.

US doesn't have this problem because their currency is the world reserve currency. The world's wealthiest currencies have the privilege of printing money to get through a crisis without inflation - where poor countries do not.

Also Sri-Lanka is badly impacted by climate change at the confluence of major weather systems. Coupled with development heading off into the hills this means they're getting absolutely hammered by floods.