`kotlinx.serialization` plugin in `build.gradle.kts` isn't caught up by the Idea IDE

Question

I'm currently trying to set up kotlin serialization for my project, and keep getting this error from the Idea IDE on usage of @Serializable decorator

kotlinx.serialization compiler plugin is not applied to the module, so this annotation would not be processed. Make sure that you've setup your buildscript correctly and re-import project.

My build.gradle.kts contains that, which is just right according to the setup guide in their repo:

plugins {
    kotlin("jvm") version "1.6.10"
    kotlin("plugin.serialization") version "1.6.10"
    java
}

dependencies {
    implementation(kotlin("stdlib"))
    testImplementation("org.junit.jupiter:junit-jupiter-api:5.6.0")
    testRuntimeOnly("org.junit.jupiter:junit-jupiter-engine")
    implementation(kotlin("script-runtime"))
    implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:1.3.2")
}

It does compile and run as intended, the example in the repo i linked above works just right. But IntelliJ Idea still keeps showing me this error.

I've tried reloading gradle project, invalidating index, and restarting my IDE few times.