How can one access the source editor in Cloud?

[Mr_ Beedell_ Roke Julian Lockhart _RJLB_]

All of my issues visible via the method which https://pm.stackexchange.com/questions/35810/how-can-i-view-all-of-the-tickets-that-i-have-filed-in-jira#comment45289_35811  describes (currently, https://moodle.atlassian.net/browse/MNET-89 and https://moodle.atlassian.net/browse/MDL-85265) lack the option to enter the source editor when modifying the post, and when adding comments. Because at least one of my issues utilises markup that cannot be achieved via the WYSIWYG editor, how can I modify it?

I was able to access it before the transition to Cloud.

At https://community.atlassian.com/forums/Jira-questions/Re-Re-Where-is-the-source-in-the-description-editor/qaq-p/3115862/comment-id/1149445#M1149445, I was advised to post a separate question about this, rather than ask at existent threads.