I was going to post this as a gossip post, but I felt that I am required to answer this.
To start off, I just want to be sure that you know your gyaru history. This was started as a style rebelling against the Japanese white-faced and pale is beautiful mentality as well as rebelling cultural standards. The white lips, often seen in western cultures (with dark skin) is used as blackface, but the trend started with Namie Amuro, a pop star in the 1990s.
With her tan skin, short skirts and boots, she essentially made the kogal go-to outfit. She wore white lips a few times, and the trend caught on.
Basically, the style just grew more and more shocking. The ganguros started to wear white on their eyes and lips regularly. Gonguros upped the tans, which was carried over to later styles. As manba and yamanba took over, they ended up adding more white to the look, looking scarier and more crazy. If they wanted to rebel against the standard of beauty in Japan, they had greatly succeeded.
B-gal is not based off of black culture, although brands like Baby Shoop make it seem like that’s what it is. It’s based off of R&B artists (especially those at the time the style originated (think: Beyonce, Alicia Keys, etc.) There is a difference between cultural appreciation and cultural appropriation.
Gyaru history aside, if you find the style offensive, you don’t have to do it.
It’s all a personal choice whether or not you follow the tanned styles or reject them altogether. Almost everywhere in the world there is a tanning culture, and there will always be people who take it to the extreme, gyaru or not.