In addition to having a strong master password, default client iterations are being increased to 600,000 as well as double-encrypting these fields at rest with keys managed in Bitwarden’s key vault (in addition to existing encryption).
The team is continuing to explore approaches for existing accounts.
In the meantime, the best way to protect your account is with a strong master password, see more information here: https://bitwarden.com/password-strength/