3090 is on Samsung 8nm 2+years old node so it will always be worse
While the M1 Ultra is the latest CPU, it still uses A14/M1 cores from 2020. It's likely that Apple made a lot of progress on the microarchitecture since then, plus rumors are that M2 will switch to a 4nm node.
While the M1 Ultra is the latest CPU, it still uses A14/M1 cores from 2020. It's likely that Apple made a lot of progress on the microarchitecture since then, plus rumors are that M2 will switch to a 4nm node.