Hi, welcome to 3FC
Unfortunately that is the problem with diet pills, they do not really help with weight loss. They are generally stimulants which lose their effectiveness, and often contain laxatives or diuretics which mimic weight loss but do not affect fat loss. Your best bet is to watch portion sizes (or count calories or some other method of portion control) and increase your activity levels. That's the only thing that has been proven to cause weight loss and will also keep it off as long as you continue to practice these methods.
I think it's great that you are a vegetarian! But even vegetarians gain weight unfortunately
We have a vegetarian diet forum that might interest you here
Regarding the Japan Lingzhi, I found a list of ingredients but can't find anything to prove that they work or even what they do. They are rather mysterious. There is no record of clinical testing to show they are safe or effective. They contain laxatives, so after some time spent in the loo you might think you lost weight but not the right kind of weight
I'd personally avoid them. I also found one review where a woman was made ill by them.
The main problem with products like this is that they are not regulated by the FDA so they can contain almost anything and make almost any claims and get away with it. The actual ingredients of the product may not even match what is on the label. In independent testing, many supplements contain zero amount of what the label states, or many times more than what is stated and could be dangerous. These products, particularly those from Asia, often contain dangerous contaminants such as lead or arsenic or pesticides.