One of the new male swimsuit options (that looks like briefs, in the image below) only allows color swatch changes on the top liner of the suit, and not the bottom. While the main color and sub-color do change, the sub-color doesn’t adjust the bottom liner of the swimsuit - only the top.
I thought this was a bug at first but then I noticed both the new swimsuits limit which dye channels can be changed. I would think the top liner dye channel would be the same as the lower seam dye channel. You can see in the image below, if I want to dye the red swimsuit to a deeper red, I can’t because the original bright red still shows up. In other words, the bottom strip seems limited to the original color selection and you can’t customize it using the sub-color option. I also included a picture of the green to show that if you want a different green, it will clash with the bottom liner.
I really like deep colors or earth tones - not bright - so not being able to use them is really disappointing.

