According to the official governance forum, a new Aave community proposal proposes adding stEUR as a pure collateral asset on the Aave V3 Ethereum pool.
stEUR stands for staked agEUR, a decentralized euro-pegged stablecoin minted by Angle Protocol.
The proposal states that while stEUR and agEUR have relatively small market caps ($5 million and $20 million respectively), making stEUR a capped collateral-only asset will allow it to grow in a controlled environment, minimizing Risks of the Aave protocol.