why are you so sure that this has anything to do with LUKS ? Did you test by running the benchmarks or even --benchmark --benchmark-all ?
did you try to use the beta from https://hashcat.net/beta/
I assume you are using linux and the most recent nvidia driver, but please always mention important info like this
did you try to use the beta from https://hashcat.net/beta/
I assume you are using linux and the most recent nvidia driver, but please always mention important info like this