It’s not unsafe. You have a version on playstore. Basically, it allows you to use privileged APIs which would need manually using ADB or root. Some of my apps like Darq, droid-ify, takostats, and lemmy-redirect use it perform actions like enabling link handling, performing app installation, applying force dark mode without requiring root, etc.

Here’s the description pulled from fdroid:

using system APIs directly with adb/root privileges from normal apps

When developing apps that requires root, the most common method is to run some commands in the su shell. For example, there is app uses pm enable/disable command to enable/disable components. This method has very big disadvantages:

• Extremely slow (Multiple process creation)

• Needs to process texts (Super unreliable)

• The possibility is limited to available commands

• Even if adb has sufficient permissions, the app requires root privileges to run

Shizuku uses a completely different way. The most important feature Shizuku provides is something like be a middle man to receive requests from the app, sent to the system server, and send back the results. To the app, it is almost identical to the use system APIs directly. But it’s much faster as it hooks into the system directly.