Plugin validation failed because a compatible plugin could not be found

IntelliJ Platform Plugin Verifier
1

Sometimes, plugin verification fails because a compatible plugin cannot be found. This situation occurs the same way in both local verification and Marketplace verification.

Here is my config:

dependencies {
    intellijPlatform {
        pluginComposedModule(implementation(project(":lang:uast")))
        compatiblePlugin("SequenceDiagram")
        intellijIdea(prop("platformVersion")) {
            useCache = true
        }// publish
        bundledPlugins("com.intellij.java", "org.jetbrains.kotlin", "org.intellij.groovy")
        compatiblePlugin("org.intellij.scala")
    }
}

intellijPlatform {
    pluginConfiguration {

      // ...
        ideaVersion {
            sinceBuild.set(prop("sinceBuild")) // 252
            untilBuild = provider { null }
        }
    }
   
    pluginVerification {
        ides {
            recommended()
        }
    }
}

Today(April 12), Run verifyPlugin locally, recommended() found three versions for verification: IU-261.23567.28, IU-253.32098.37, IU-252.28539.33.
The result:

IU-253.32098.37 against vanstudio.sequence.java:4.0.6: 1 compatibility problem, some of which may be caused by absence of optional dependency in the target IDE IU-253.32098.37. 4 usages of experimental API
IU-252.28539.33 against vanstudio.sequence.java:4.0.6: Compatible. 4 usages of experimental API
IU-261.23567.28 against vanstudio.sequence.java:4.0.6: Compatible. 1 usage of deprecated API. 4 usages of experimental API

The reason for the IU-253.32098.37 verification failure is:

Dependencies used on verification details
vanstudio.sequence.java:4.0.6
+--- (failed) org.intellij.scala (optional, v1): Unavailable

What is the principle of compatiblePlugin("org.intellij.scala"), and why does it sometimes find compatible plugins and sometimes not?