Some of the big disadvantages of React Native for building mobile applications are given below:

React Native is still new and immature: React Native is a new framework in Windows, Android, and iOS programming languages. It is still in the improvement stage, which can have a negative impact on the apps.
Learning is tough: React Native cannot learn quickly, especially for a fresher in the app development field.
It Lacks the Security Robustness: React Native is an open-source JavaScript framework, which is fragile and creates a gap in the security robustness. When you are creating banking and financial apps where data is highly confidential, experts advise not to choose React Native.
It Takes More Time to Initialize: React Native takes a lot of time for initializing the runtime even if you are using the hi-tech gadgets and devices.
Existence is Uncertain: As Facebook develop this framework, its presence is uncertain since it keeps all the rights to kill off the project anytime. As the popularity of React Native rises, it is unlikely to happen.

As of my last knowledge update in January 2022, React Native had some disadvantages, but it’s essential to note that the framework evolves, and updates may have addressed or mitigated some of these issues. Here are some common disadvantages associated with React Native up to that point:

Performance Concerns: While React Native can achieve near-native performance, it may not be as performant as fully native applications, especially for graphics-intensive or highly complex applications.
Native Modules Integration: Integration with native modules might be necessary for certain functionalities. This can add complexity to the development process and require additional expertise.
Learning Curve: Developers who are new to React Native may face a learning curve, especially if they are not familiar with React.js. Additionally, understanding the interaction with native components might require additional effort.
Limited Access to Native APIs: Some native features and APIs may not be readily available in React Native. Developers might need to use third-party libraries or write custom native modules to access certain device-specific functionalities.
Debugging and Tooling: Debugging React Native applications can be more challenging than debugging native applications. The tooling might not be as mature as what’s available for some native platforms.
Large App Size: React Native apps might have a larger file size compared to native apps, as they include the React Native runtime. This can impact download times and storage requirements.
Community Modules: While the React Native community is active, the availability and quality of third-party modules can vary. Some may not be well-maintained or lack necessary updates.
Version Compatibility: Updates to React Native may introduce breaking changes or require adjustments to existing code. Managing version compatibility can be a concern for larger projects.

It’s crucial to keep in mind that React Native is continually evolving, and newer versions may address some of these issues. Additionally, the development landscape is dynamic, and the community often finds solutions to challenges through libraries, tools, and best practices. Always refer to the latest documentation and community discussions for the most up-to-date information.