The bug:
If you go to your Mojang account settings at https://account.mojang.com/me/settings you will see that there is a space missing between "Security questions" and "Your account is secure"
See attachment for example.
Attachments
Comments 11
80 is release, 81 is pre-release, 82 is alpha and 83 is nightly - seems to not occur in 83 at the moment, which is what makes me believe it was/is an issue with Firefox.
I went ahead and tried on a different device and the space was there, therefore, the issue likely lies with my main device, and which means it isn't a bug or at least not one that affects many people.
Can't seem to reproduce this?