Product Page: Font for Options is Different on Mobile (Includes Workaround)

Known Issue|We’re investigating this issue.
We're aware of the issue and are currently gathering more information regarding this matter.
Meanwhile, you can do the following to resolve the issue:
The font displayed on mobile for product options is currently taken from your site’s Paragraph 2 style instead of from your design selections. 

To fix this, you can edit the Paragraph 2 style in the theme manager.