I'm seeing indications that this is sometimes related to language translation using GTranslate.io [1]

> We use XNUMX variable instead of all numbers in our edit interface. For example "10 cents" in your original text is represented as "XNUMX cents" in the edit interface, so if you translate "XNUMX cents" once, the same translation will be used for all similar phrases like "11 cents", "18 cents", etc. This helps to do less work.

[1] https://docs.gtranslate.io/en/articles/1348921-how-to-edit-t...