Yes, there are. Public restrooms are public spaces meant for basic personal hygiene needs. Any form of sexual activity in such places is inappropriate and unethical. It violates the privacy and comfort of other users, and may also be against public decency laws.
There are definitely ethical concerns. Public restrooms are not private areas for sexual encounters. It can make others who are using the restroom for its proper purpose feel uncomfortable and violated. Moreover, it can give a negative impression of the gay community when such inappropriate behavior is associated with it, which is unfair as the vast majority of the gay community behaves appropriately in public.
Look to Chapter 28 for the clearest answer. It begins with The next evening, Jiang Yan drove home seething with rage., keeps building through Before he even entered the dining room, he shouted angrily, "Lili, you did..., and lands on Lili then kicked his knee hard..
If you want the clearest chapter reference, go to Chapter 8. Early on, The resentment that had barely calmed among the crowd surged back two...; later, the chapter leans on Some of them were relatives of the Jiang Family, who felt it improper to....
The best chapter pointer here is Chapter 28, "Beaten Up Again". It opens with The next evening, Jiang Yan drove home seething with rage. and closes on Lili then kicked his knee hard..
Chapter 774, "I've Found Good Guests for You", is the clearest early answer because it turns Sister's situation into a concrete plot event. It opens with Jiang Li hadn't failed to notice. and closes on Why did Shiguang go to Jiang Li's dressing room?.
Chapter 763, "It must be Jiang Li who tied her up!", is the clearest early answer because it turns Shang Shaojing's situation into a concrete plot event.
Chapter 937, "When Did the River Moon First Shine on People [Extra: River Moon Chapter]", is the clearest early answer because it turns Shang Shuyue's situation into a concrete plot event.
Chapter 62 is the strongest chapter-level answer because it starts from Sitting on the edge of her bed, she pondered for a while before lifting... and follows through on Jiang Li reached in, pulled out a piece of paper, and slightly raised her....
Chapter 28 is the strongest chapter-level answer because it starts from The next evening, Jiang Yan drove home seething with rage. and follows through on Lili then kicked his knee hard..
Chapter 1 is the strongest chapter-level answer because it starts from Jiang Li, I'm warning you, don't set your sights on Yinwan anymore, or... and follows through on Yet before she had the chance to teach her a lesson, the male lead arrived....