It’s reasonable for an app like this to need root, but also reasonable for everyone to ask for third-party verification of anything they’re granting administrative access to their devices.
Izzydroid’s security policy appears to be primarily based around automated scans that enumerate badness, and has far fewer users than the official F-Droid repository making it less likely that problems will be noticed, reported, and acted on.
Is there more reputation information about this app available?