Most 4K REMUXes are 23.976 fps. Ensure the subtitle file you download isn't intended for a 25 fps PAL source.
I’m looking for a clean set of subtitles (SRT or ASS) specifically timed for the release. subtitle Oblivion.2013.2160p.BluRay.REMUX.HEVC....
On subtitle databases, look for "UHD," "4K," or "REMUX" in the file name. These are almost always timed to the same master as your file. Most 4K REMUXes are 23
Searching for the right subtitles for a high-spec release like (or similar REMUX versions) can be tricky because timing is everything. Since REMUX files are uncompressed rips of the original Blu-ray, you need subtitles that match the exact frame rate and "retail" timing of the disc. look for "UHD