Irregular teeth, which is the SiS technology of shimano, make the speed change smoother through different tooth types.
This is Shimano's patented technology until the end of 1990s. Later, when the patent expired, SRAM, SR, and other manufacturers began to use this technology to improve the competitiveness of their products.
Not only the toothed plate, but also the flywheel. The derivative of SiS is irregular teeth.
So your condition is completely normal.