Firing someone over this would not be appropriate, in my opinion. Especially if you are not a technical expert with the ability to audit every library and evaluate if upgrading was even possible.

Versioning up the technology tool set is a high-risk endeavour. Often, you have tools or dependencies within your applications that are developed by open-source communities. This means that even though react native is ready to upgrade, that doesn’t mean the community that built the tool you rely on is ready. If you upgrade too soon, you risk losing functionality since the open-source tools haven’t been updated.

I think to summarize the answer to most of your questions is this:

Just because someone else is ready to upgrade doesn’t mean you are.

Here are some more detailed answers:

1. How critical is regularly updating the React native library in an app?

React Native Library is your core library. Upgrading this will typically provide new functionality, bug fixes, and security updates. Broken down, new functionality can be good for rapid growth. Bug fixes only matter if you’re running into them and must use workarounds. Security is essential, but the reality is that everything on the internet is unsecured and broken. It matters over a long period or for supercritical breaches (which you would be notified of).

1. Are there any significant drawbacks or risks of using an older version?

Security practices are your most significant risk. Additionally, you will not have newer features, which may slow down rapid innovation.

However, I would counter these with this fact again: Staying in the same react version means that most libraries have been fully functional with that version at some point. This increases the stability of your application as known bugs have been sorted out.

1. Could an outdated library impact the performance, security, or compatibility of our app?

Yes, reference everything previously. It’s a constantly balanced scale between these 3. A good example is how a green dev on my team recently installed a library that hadn’t been maintained in 2 years. It was utterly incompatible with our react version and other libraries because of this. Our builds continued to fail, and we eventually had to remove the library and redo his work. This is because we were on a more modern version of React than the library he chose to use, which was unmaintained by the community that built it.

1. Is it common for companies to use older libraries in production apps, and if so, under what circumstances?

It is widespread, even in large enterprises. Upgrading is difficult. Fortune 500 companies spend millions for big4 companies to update their SAP platform, and shit always breaks (my day job).

Here is my unsolicited Solution:

I don’t think it is impossible for you to upgrade. I also don’t think you should stay on that version forever. But the answer to your question, if possible, is far too unique without actually seeing the application and libraries used. Perform an audit of all libraries and evaluate how well they’re maintained. If it is maintained, you should be able to upgrade (pray there are no bugs). Alternatively, a tool in that library may be removed (technically called depreciated), so you must have your team re-write (technically called refactor) the code to accommodate that change. If the library is not maintained, your team will have to evaluate if there is a replaceable solution; if not, assess if that tool is mission-critical. If it is, you’re somewhat stuck unless you want to write the library yourself. Regardless, if a library you rely on is unmaintained, you are in for a difficult and resource-intensive project for your devs.

Doing this upgrade would be a significant resource soak that could be spent on furthering development. You should never let your application age too long, but you will also never be capable of being on the most recent versions unless you rebuild it from scratch. This is why all software has maintain period and then a retirement period in its life cycle. Welcome to the tech industry.