This is because Fast Transition (FT) is a feature that allows 802.11r-capable clients to roam faster between access points by reducing the authentication and key exchange time. FT can be configured in two modes:
adaptive and over-the-DS. Adaptive mode is recommended for mixed environments where both
802.11r-capable and non-capable clients are present, as it allows the access point to negotiate the FT mode with the client. Over-the-DS mode is only suitable for environments where all clients are 802.11r-capable, as it requires the access point to communicate with the previous access point over the distribution system. FT + PSK is a security option that enables FT with pre-shared key (PSK) authentication, which is a simple and common method of securing wireless networks. WPA2-AES is an encryption standard that provides strong security and privacy for wireless networks. The source of this answer is the Cisco ENCOR v1.1 course, module 7, lesson 7.2: Implementing WPA2 and WPA3.