Wise protects customer funds with several measures:
They keep customer funds separate from Wise's operating capital to avoid using your money for daily operations. Most of the money is in government bonds and money market funds held in top-tier banks with low default risk. Wise is also licensed and regulated by financial authorities in their operating countries to comply with strict customer fund rules.
However, unlike FDIC-insured bank accounts in the US, Wise accounts are not federally insured. If Wise fails, your money isn't protected by the government.
Wise may be a good option for a portion of your emergency fund if you value easy access and faster international transfers. Since Wise lacks FDIC insurance, it's not recommended to store your entire emergency fund there. For maximum security, keep a core portion of your emergency fund in a traditional bank account with FDIC insurance (up to a limit).
If you have additional information or insights, don't hesitate to share in the comments.