Currently, the pom has the symbol-processing-api dependency listed as runtime but SymbolProcessorProvider is part of the public API:

class KotlinSymbolProcessing(
    val kspConfig: KSPConfig,
    // public usage of symbol-processing-api here
    val symbolProcessorProviders: List<SymbolProcessorProvider>,
    val logger: KSPLogger
) { ... }

The workaround is to manually add symbol-processing-api as a dependency but it'd be nice if it were modelled in the pom.

Edit: same is true about symbol-processing-common-deps