Therefore sometimes a preposition can be followed by a subject pronoun, right?"Depending" is not the subject of the sentence. In the original construction, the subject is unclear or nonexistent. That is why I suggested an alternate construction.
But this does not address your original question, which was whether to use "who" or "whom." In an English phrase, it is correct and natural to say "depending on who is doing the singing ..." It is not correct to say "...depending on whom is doing ..."
Only if the subject pronoun is in a complete clause where the whole clause is the object of the preposition.Therefore sometimes a preposition can be followed by a subject pronoun, right?
The bold text is a complete clause - regardless of "the person in charge of the party" - and the subject within the clause is "who", the verb is "is". You can't have a subject be "whom" - whom is only ever an object. So what follows the "of" is not "whom" but "who is in charge of the party".Things are always going to be pretty bad at the moment, regardless of who is in charge of the party.
The use of ‘who’ is clearly right in that sentence and it’s right after a preposition, so why is that correct?