I know many extensions have full access to any site you visit, but I specified LinkedIn for mine, so when you install it, you are warned that it can access all your data on LinkedIn, but no other sites.
On Chrome extensions, minor bugs (or minor bugs in the libraries you depend on) might end up having far worse consequences. Read/write access to only linkedin.com can still leak a decent amount of unwanted information in case there's an exploit.
I don't use any external libraries, I wrote all of the code in the extension, and the only external requests made outside of the extension are to Google Fonts, so I wonder if it'd be possible to infect this extension.
https://www.wired.com/story/chrome-extension-malware/
edit: tried your extension out and I really liked it! thanks for sharing