You are seeing npm deprecation and peer dependency version warnings from Gatsby's dependencies. This does not necessarily have anything to do directly with gatsby-plugin-react-helmet or other packages you're adding, npm just validates the entire dependency tree also when adding new packages.

The messages you're seeing are not errors, they're warnings, and any packages you install should mostly work just fine.

Frameworks like Gatsby depend on a great number of other npm packages that in turn depend on even more transitive dependencies, creating a vast dependency tree. Maintainers need to constantly update their own npm dependencies to fix newly found security issues, clear deprecation warnings, resolve peer dependency version conflicts, etc. Otherwise people who install their packages get warnings like this.

The reason these warnings are starting to pile up when installing npm packages from the Gatsby ecosystem is that Gatsby's development and maintenance work has slowed down considerably after being acquired by Netlify.

Gatsby used to be actively developed by a team working for Gatsby Inc. until the company was acquired by their competitor Netlify in February 2023. Shortly after this they laid off most of the Gatsby team. There are still Netlify engineers working on Gatsby and making some releases now and then, but dependency rot is still an ongoing problem, amplified by the fact that many of the popular Gatsby plugins are owned by individuals who have since moved on to other platforms.