Wellwisher There are quite a few extensions:
- Akismet
- FoF Ban IPs
- FoF Stop Flarum Spam
- FoF Spamblock
- FoF Disposable Emails
- Spam Prevention
- FoF reCAPTCHA
- Turnstile
- Mail Filter
I might forget some of them, personally I haven't tried them all, but in my experience Spam Prevention is the most complete (actually it has compatibility with multiple extensions like FoF Spamblock to automate some processes), it's worth to take a look and configure it in depth according to your needs, if you also use reCAPTCHA/Turnstile for account signups, in general you should notice an improvement.