I remember that there was an update of Jira: https://<name>.atlassian.com not long ago and it changed https://bugs.mojang.com as well.

Despite this Mojira site has a custom setting for apperance (including colour) to let it look different, some places, including the "Log in" button, the "Create" button at the bottom of the "Create issue" page and the thin line besides a comment (shown in the screenshot of the comment under WEB-1098) remains the same blue colour as it is in most Jira sites such as https://jira.atlassian.com. This is inconsistent with the red colour in other places such as the "Create" button at the top of the main page, and the entire red-and-white appearance of this site. And most importantly, these blue places weren't blue before the Jira update occurred.