Based on this conversation.

When a mentor sets themselves away, Growthexperiments-homepage-mentorship-questionreview-header-away is displayed to their mentees when they want to send a message to their mentor.

However, this message is not really visible (bold with other bold text around) and may benefit of a different presentation:

This sentence might be a te a better place on the mentor module itself, with some improvements:

• T311063: Growthexperiments-homepage-mentorship-questionreview-header-away don't show the duration of the away time
• T311064: Growthexperiments-homepage-mentorship-questionreview-header-away should provide a link to the replacement mentor