Q.hibiscus plants
Our Hibiscus plant is losing buds before they open. There are some yellow leaves as well. While we have sprayed for insects and fertilized, we noticed that some leaves now have black spots on them. Looking for care advice.
Thank you

It is common for Hibiscus to attract insects, a good treatment is Neem OIl.
I would use weekly during the growing months.
Here are some links for you.
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/hibiscus-flowers-hibiscus-blossoms-falling-off-plant.htm
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/answers-to-what-causes-hibiscus-leaves-turning-yellow.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm