Been thinking of a good idea for a mobile application is easy these days. The market is massive. There always be a type of customer that will be interested in a certain kind of application. But, thinking innovating something unique or thinking of an idea is not actually be hard part creating an application. The hard part is the mobile app development or finding someone that will do that part of the process for you. There are so many common mistakes that a lot of developers make when creating a mobile app.
When talking about common mistakes, there are probably thousands of them. One way or another, you will make those mistakes. But, that is not always a bad thing. The best way to learn mobile app development is if you make mistakes along the way. That is completely healthy and normal for any business. But, there are some mistakes or problems that can set you back financially and with time. Considerable setbacks that are very difficult to come from. Especially, if you are working with a tighter budget or if you have a start-up company.
To help you make this part of this entire project a little less stressful and smoother, I decided to write a 2021 guide for the most common mobile app development mistakes that you have to avoid. Make sure you read through the entire article to understand why avoiding them is so important.

Making the UI similar to a desktop program
Whenever I download applications from the PlayStore, I noticed that developers always make that same mistakes that ruins the experience for me. Obviously, this is my personal experience, but I also believe that objectively has an impact on the experience of an average user.
You are creating something that needs to be optimized as much as you can for a small device such as a tablet or phone. Everything you know about desktop UI, you can forget about that. Of course, there are some elements that are the same or very similar between these two platforms, but most of them are not.
So, if you want a smooth UX for everyone, I would suggest focusing on creating something that will be functional for phones and not for larger moderators such as computers or laptops.
Copying the website design/style/UX

Online websites are very useful but only when you are working from a laptop or a desktop. Once you open up the website from a phone or tablet, the whole experience is much worse. It is not too bad, especially the website has been optimized for phones, but it can never be good as an application.
Applications are made for users that prefer or completely rely on mobile devices. The entire point of these programs is to make the access toward certain services and products be easier for customers that try to buy from their phones.
Have you ever tried to check out on any kind of website on your smartphone? If you have then you probably know that the entire checkout experience is not exactly smooth.
However, when trying to make the user experience smoother and better by creating an application that will completely replace the website for certain devices, it is very important not to copy the websites UX, its design and style. In fact, you should aim to make it as different as possible from your webpage.
People are coming to use this app because they hope it will provide better UX. They did not download it to be greeted by that same UX and the same design.
If you are having trouble getting creative and creating an application that will be a lot more unique and different from your website, you should probably consider hiring a professional team that can help you develop an iOS, Android, or a web app as suggested by EGO Creative.
With the help of a professional team, I am sure that you will not make these common mistakes.
Long animations

Almost every developer I know loves the idea of creating animations that are satisfying to look at, smooth, and very stylish in some unique way. They believe that such a complex animation makes for a better UX. And sure, that is true. Well-designed animations make users happy.
However, there is a certain threshold that should never be overstepped. This is not my opinion or something subjective, this is entirely subjective. That threshold is about the length of animations. Sure, they are pretty, but if they are too long, they can easily become frustrating to users, especially when they are applied to mobile applications.
That is why it is so important to avoid making animation that lasts too long. Otherwise, you might actually lose a lot of your clients just because of this.
Developing only for Android or only for iOS
These days, I regularly see that developers are planning to build an application for either one or the other platforms. Not often do you see someone planning to push the release for both Android and iOS. I know it is probably less work to build apps for two different platforms, but you also have the possibility to obtain twice the number of customers.
So, if you do have a plan to release on both of these operating systems, I would suggest that you do it at the same time. You should not prefer one operating system over the other because that might have an impact on your customers. Everyone deserves the same treatment.
Too many features
Most developers want to make their own mobile application with rich with as many features as possible. But, in reality, there is no need for them. Cluttering a nap with unnecessary features will only make it slower and very unresponsive. So, keep it simple and if there is a need for such a feature in the future, you can always add it later.
As you can see, there are a lot of jumps and hoops that you need to get through during app development, but if you avoid these mistakes, I am sure that everything will go smoothly.