It is normal. Frontend code is much harder to test than backend. It also has a visual aspect that backend doesn't have. Your API server doesn't care about cross browser specs, or screen resolution. So when a new iPad comes in, you don't have a new dozen of bugs. Also frontend lacks developers, so it happens that there are plenty of intermediate developers who have a junior level, leading to spaghetti code, and unmaintainable code, and poor management pushing unrealistic deadlines.