The image generated when you share your personal “Year on iNat” statistics on Facebook has missing characters (replaced with question marks). Those are non Latin characters - Cyrillic (“наблюдения” I suppose) and one Latin character with a combining diacritic (“ǎ” in my name). I guess the characters are missing in the font used to generate the image.
Attached is the generated image for my Facebook share. And this is my stat page where everything is rendered correctly (in Bulgarian as per my website settings):