Hi @HunterEuchaski and @DBroderick,
I’d like to share this similar post from @danmoyle that might help you “Protect Against Spam Accounts”.
Also, from reading the previous posts, it sounds like you have taken the right course of actions so far.
I checked internally for you and currently, you can enable Captcha and block specific email domains or free email providers.
Those are the options that we have to control bot/spam submissions. However there isn’t much more action we can take from our end to prevent them unfortunately.
One thing to note is that when captcha is live, you may see some spam submissions come through. That indicates they managed to bypass Google’s security filters and didn’t trigger as suspicious for some reason.
I hope this helps!
Have a nice day!
Bérangère