Unresolved reference: constraintlayout

app\build.gradle.kts に以下を追記。

dependencies {
    implementation(libs.androidx.constraintlayout)

ビルドでエラー発生。
Unresolved reference: constraintlayout

解決

gradle\libs.versions.toml　の[versions]セクションに追記

[versions]
constraintlayout = "2.1.4"