It looks like Lemmy 0.18.0 has some quirks:

1. Captcha is broken, despite the devs rolling back their plans to get rid of it. We got spammed with bot sign-ups before enabling the captcha, so I have enabled requiring registration applications until it gets fixed.

I personally hate registration applications, but I hate spam bots even more so it's a necessary evil for the time being.

2. Trying to delete your own account fails at the moment - I have submitted a bug report on this. I hope nobody here wants to delete their accounts, but if you do and you can't wait for this to be fixed, let me know and I'll delete it manually.

Other bits and bobs are funky too, but these seem to be the main issues that I've come across so far.