Good eye! The space in "No. 12" would traditionally get a thin space [0] in professionally typeset documents, which is smaller than the standard space used for inter-word and inter-sentence spacing.
The solution here is to fix the sample text itself to use U+202F (NARROW NO-BREAK SPACE,  ). As opposed to the standard width no-break space it currently has for "No. 12" and "Fig. 7".