I don't think so. I couldn't find anything about delta.exchange launching defi. According to data, they were in business since 2018 and there were no signs of rebranding during that time either.
Perhaps you have an exact link of the suspected exchange related to the failed defi?
I search on Coinmarketcap and find
Delta exchange with only one trading pair (given my Coinmarketcap SOL / USDT)
When I visit the exchange, there are more trading pairs so it seems the exchange has very low trading volume on most of their trading pairs.
A little bit more pairs on
CoinGecko for Delta spot trading