So that URL https://url3447.singularitydao.ai/ls/click?upn=stuff is not something Discourse will generate out of the box. There is something between Discourse and the final sent email that is manipulating the links in emails. Maybe your company enabled a tracker feature.
I signed up to your forum and looks like you are actually using SendGrid for outgoing emails, and not GMail. Check your SendGrid config and disable tracking for Discourse emails.
Either that or fix the tracking domain, as url3347.singularitydao.ai doesn’t have a corresponding DNS entry.