I reported this issue to support who advised to raise this as a feature request.
The new knowledge editor used to have the option of "CODE" within the "T" formatting selector. Having this within the editor provides a useful tool to our writers who may not remember to use shortcut keys or edit the source code to format text as inline code.
We recently noticed this option has been removed.
As shown in this article https://support.zendesk.com/hc/en-us/articles/7595840358042-Transitioning-to-the-new-article-editor, under the "Enhanced article editing tools" section which shows the T option as having formatting tools.
Please include the incline code option in the "T" format option of the new editor.