Linking error while compilation mode is "Whole Module"

I was testing my framework APIs. My framework has the following sample code

open class TestManager {

let appendStringHandler: (String, String) -> String

public init(appendHandler: @escaping (String, String) -> String = TestManager.appendStringObject(text1:text2:)) {
    self.appendStringHandler = appendHandler
}

public class func appendStringObject(text1: String, text2: String) -> String {
    return text1+text2
}

public func printString() {
    print(appendStringHandler("test1", "test2"))
}

}

I am creating an object like this let test = TestManager() in my project which is using the framework.

I am getting the following error while building in Debug mode and in Xcode 14.3

Undefined symbols for architecture x86_64: "_$s17ReusableComponent11TestManagerC18appendStringObject5text15text2S2S_SStFZ", referenced from: $s17ReusableComponent11TestManagerC13appendHandlerACS2S_SStc_tcfcfA_S2S_SStcfu in ViewController.o ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation)

After some investigation found out that changing the debug Compilation Mode to "Incremental" is fixing the issue.

Observations: Xcode 14.2: There is no issue when Compilation Mode is "Whole Module" in Debug/Release both Xcode 14.3: Having issue when Compilation Mode is "Whole Module" in Debug. Release Mode doesn't have any issue with "Whole Module" mode.

I was wondering what changed in xcode 14.3? Please let us know how can I stick with the "Whole Module" compilation mode without the error.