Upgrading everything
Upgrade everything now. The first finding from any code analysis or external security scans is reporting any versions that are out of date. Hosted services might take care of some of this for you, but you must regularly update any versions you control. Operating systems, web servers, programming languages, and all their related packages and extensions must be periodically upgraded. Schedule a repeating task to stay up to date with the latest patches and releases. Dependency management systems such as Poetry can ensure packages stay up to date during development.
While it is easy to say you should keep everything up to date, performing those upgrades and resolving any dependencies can be very difficult. Compared to adding new features, performing an upgrade that gives no tangible benefit can be a lower priority since, in the best case, your application works exactly as it did before.
In addition, making low-level changes like these risks introducing serious...