See the pale yellow "box" below the "Add Comment" button. Y'all know it's the "comment must have at least 15 characters" notification, and it's just cut in half and no readable text is shown.
Plus, the "dismiss" button is slightly visible (its top border)
Note: this is triggered when you enter more than 15 characters in the comment box of an answer, but after compacting (continuous and leading/trailing spaces) it is too short.
Plus, when such bug happens, the whole answer becomes scrollable:
Chrom 69.0.3497.100 on Android 8.1.