I mean, if you’re junior and you’ve just learned JavaScript, it’s not difficult. I’ve met a lot of monied people who seem to think a junior dev with a few weeks of JavaScript training is equivalent to a senior engineer with a degree. It never works out, at least not for the smart people.
If anything, that shows a lack of proper hiring decision on you and your team's part.
I do, however, agree that their practices are horrible (just look at their console, they're console.logging random things, running the dev mode of Firebase, and fetching some USD conversion call 10x on load with no caching) and they're lucky Google bailed them out at the last minute.
Hey, friend! I had no control over hiring for that gig.