As mentioned in the comment, it looks like the issue is because the Kotlin version and KSP version in your project don’t match.

You're using Kotlin 2.1.0, but the KSP version you used is for Kotlin 2.0.21. These versions need to match to work properly.

If you want to stay with Kotlin 2.1.0, update your KSP line like this:

id("com.google.devtools.ksp") version "2.1.0-1.0.29" apply false

If you don’t have a good reason to stick with Kotlin 2.1.0, you can update to the latest version (like 2.1.21). Then use this line instead:

id("com.google.devtools.ksp") version "2.1.21-2.0.1" apply false

To see which Kotlin versions work with which KSP versions, check this link