@”Kapitán Denis” Srbsko-Slovenský has different meaning to me. That basically Slovak heavily influenced by Serbian. It’s spoken in some minor Slovak communities here. It’s mostly thing of vocabulary, but also using some grammatical constructs foreign to Slovak.
btw Đoković is a polyglot, he speaks several languages and has a gift for it. Trust me there is Serbian accent. It’s usually due to those raising and falling tones in accents I’m mentioning all the time. And yeah, Serbs mostly can’t pronounce H.