I do not really understand what your post is really about as you meant that USD0 is not a stable coin. It was said to be a stablecoin and it is still pegged to United States dollars. Since it was created, its price has not really increased and decreased more than United States dollar price.
You most likely confuses USUAL which is a governance token
https://coinmarketcap.com/currencies/usual/ with ticker $USUAL
and Usual's USD0 which is stablecoin
https://coinmarketcap.com/currencies/usual-usd/ with ticker USD0
when im talking about USD0 and USUAL it's different token and OP also mistake USUAL for USD0 which is different.