GGB It follows the format, so there is no single right answer. As typical shapes: casual dining runs roughly balanced between kitchen and floor, fine dining carries more staff per cover with deeper service layers, counter-service formats tilt kitchen-heavy, and a cloud kitchen is almost entirely back-of-house. Copying a ratio from another format is how rosters go wrong — derive the split from your own service model and judge the total against covers and revenue.
From How Many Staff Does a Restaurant Need? The Staffing Math — the full reading, with the method behind this answer.