I had a quick look at your plugin sources.
If you add this right above instrumentationTools() in your build.gradle.kts:
bundledModule("intellij.libraries.ktor.client")
bundledModule("intellij.libraries.ktor.client.cio")
// instrumentationTools()
and this in your plugin.xml:
<depends>intellij.libraries.ktor.client</depends>
<depends>intellij.libraries.ktor.client.cio</depends>
then you can compile even when you remove your own dependencies to KTOR.
It’s usually strongly recommended to not bundle libraries, which are bundled with the IDE, in a plugin. It’s possible to get weird classloader errors, for example.