When you connect to a Wi-Fi network that’s not secure, i.e., that uses WEP or TKIP for encryption, Windows 11/10 will display this message. These security standards are older and have known flaws.
I keep seeing people say that "WPA 2 supports AES and WPA doesn't," but I've found that to be untrue. Before WPA2 came out my Thinkpad could do "WPA/AES" instead of "WPA/TKIP" (the latter presumably ...