It seems to keep the old behavior because you have a cache in your browser.
Are you using Chrome? Check the operation in the Incognito Window:
Also, the settings in Cloudflare are currently here: (I also use Cloudflare!) anigiri.ga(your domain) - SSL/TLS - Edge Certificates - Always Use HTTPS to “ON”
I have the same issue but am unable to switch to cloudflare since the domain is used by others as well. The https redirection works on the .glitch.com url but not through the custom domain. Is it the case that the only way to get forced https when using a custom domain is using a tool within the custom domain’s DNS provider?
Sorry for the Necro… just realised it isn’t 2020 anymore :'o