Pretty sure Darktable only supports openCL and not Metal for MacOS.
OpenCL is unsupported for M1/2/3/4/5, which makes RAW file processing, batch workflows, basically everything, unusably slow.
Unless something has changed in the past few months, Darktable is dead on MacOS with no fix in sight.
I use it on Mac - I didn’t notice too much. There’s some GPU usage, I assume Apple still has some deprecated OpenCL drivers kicking around that it knows to use.
I used Darktable on Mac yesterday
OpenCL is deprecated, not unsupported, on MacOS and may be removed at some point, but it absolutely does still work for now. If you don't have OpenCL acceleration, it's a bug.