So, I am (more or less) forced to use Chrome for work, although my default browser is still Firefox (with a nifty little extension called OnChrome that automatically redirects/re-opens all links for specific domains set to open in Chrome with a specific profile instead – a huge shout out to @Gervasio Marchand)…
But within several of the web-based programs my employer uses, it often embeds resources that point back to Google sites, documents, etc. – which then simply shows a 403 error instead of the intended resource…
Turns out was simply because of “strict” third-party cookie permissions within the browser…
Adding individual sites to allow 3rd-party cookie access (i.e. Google’s) fixes this… Of course, it unfortunately allows said sites/programs to also then access any cookie from other sites, but there’s no granular access control at this time…