aSEED conversion was part of Acala 2.0 Exodus plan, see more details here https://wiki.acala.network/acala-exodus-upgrade/ausd-seed-aseed
All CDP positions on Karura (following that on Acala) with outstanding debt will be settled at the pre-approved prices in this gov vote, collaterals for unpaid debt will become part of aSEED treasury, remaining of the collaterals will remain and can be withdrawn by the owner https://voting.opensquare.io/space/karura/proposal/QmUuHgFt4fN4iKU6JzW2utx2cykz4Er3EyhLHRwYEjDk3r
This proposal has built in a 1-week delay execution, during which CDP owners can still repay their debts and withdraw collaterals to avoid the conversion if desire.
After the conversion is completed, there will be another vote for redemption rules e.g. redemption will open after 1 year and collateral per aSEED > $1