Ignore your NVR/Hik-Connect app with regard to 'no available update' or 'latest version installed'. The update check has never worked. To add to that Hikvision now advise against using the portals as they're no longer kept up to date. That's a huge step back, as the product pages generally only show current models and the search on the Firmware Download page is hit and miss.
Your model, from your existing version and build date of 4.75.200_231110 your NVR,
appears to be the DS-7604NI-K1/4P (D). The latest firmware looks to be 4.76.010_231113 and is available on the global download page here (input 7604 in the search box and you'll see it):
However nowhere can I find a firmware that states it is suitable for the /4P model...
Going forward, I've no idea how an installer, let alone an end user, will be able to locate up to date firmware once a model is no longer sold (as is the case in the UK for your DS7604NI-K1/4P)