Bots seem to post here quite frequently, because they want to advertise links to random sites, but links are not necessary for the functionality of these comments, so I would suggest disabling links in comments, or only allow links to the proton.me hostname. Also, you could put a few honeypot fields into the registration form, as well as put a Web Application Firewall in front of the registration form, with a captcha. Both CloudFront and CloudFlare offer this functionality. Stopforumspam.com also offers an api that can be used to query for the reputation of ip addresses, emails, and usernames before allowing registration. I would also only allow registration on this site from paid Proton users. All these methods combined should cut bot submissions to nearly zero.