The version you named — — suggests a fan-made or DJ/producer extended remix (Ultimix is a brand of commercial remix services, often done by DJs like Stacy Mier or others). The "D..." could be a producer's initial (e.g., DJ Dave, D-Zire, etc.).

Peak-hour party set, following a house track or leading into a K-pop dance medley. If you can share the full DJ/producer name (the "D...") and any specific label or release date, I can tailor the write-up further. Also, if this is for a school project, blog, or track review, let me know the tone you need (professional, hype, critical, etc.).

It sounds like you're referring to a specific remix or edit of (likely the Korean artist Rosé of BLACKPINK) and Bruno Mars ' song "APT." — though to clarify, "APT." is originally a single by Rosé featuring Bruno Mars, not a Rose/Bruno Mars duet outside of that context.