After enabling lint on test sources, the NewApi lint check will be triggered in robolectric tests even if the test is configured with a minSdk lower than the API being used. To work around this issues, users are required to add a redundant @RequiresApi() or @TargetApi() annotation to their test method or test class.

STEPS TO REPRODUCE:

Enable lint in test sources inside build.gradle:

android {
    lintOptions.checkTestSources = true
}

Create a robolectric test inside src/test/...
Annotate the robolectric test with @Config(minSdk = <minsdk>) (or configure the SDK with robolectric.properties). Also ensure android.defaultConfig.minSdkVersion is lower than minsdk so it doesn't get suppressed that way.
Use an android class that was added in sdk <= minsdk (I used android.util.Size which was added in API 21 and set minsdk to 23, for example). Alternatively, annotate a method or class with @RequiresApi(<sdk>) and use it in a test.
Run ./gradlew app:lint and see NewApi failures.

Example:

@RunWith(RobolectricTestRunner.class)
@Config(minSdk = 23)
public class ExampleRobolectricTest {
    @Test
    public void createSize() {
        new Size(0, 0);
    }
}

Studio Build:

Android Studio Arctic Fox | 2020.3.1 Patch 2
Build #AI-203.7717.56.2031.7678000, built on August 26, 2021
Runtime version: 11.0.10+0-b96-7281165 x86_64
VM: OpenJDK 64-Bit Server VM by JetBrains s.r.o.
macOS 11.6
GC: G1 Young Generation, G1 Old Generation
Memory: 2048M
Cores: 8
Registry: external.system.auto.import.disabled=true

Version of Gradle Plugin: 7.1.0-alpha03