Good question. Sensei and Trim Enabler carry kernel extensions inside their bundle, but they are only used for enabling Trim on macOS Catalina and earlier. On Big Sur and Monterey, these apps interface directly with the System Management Controller to unlock Trim capability during boot time, without using kexts.
This is a modern and future-proof solution, so you can safely ignore the warning this app is giving you. We won't be removing the kext from the bundle until we bump the minimum OS requirement to Big Sur for Sensei.