Many sites now display icons using a custom font. Firefox might not be downloading and using that custom font for one of two reasons:

(1) Firefox set to use your preferred fonts instead of the page's font; or

(2) Firefox set not to download fonts.

For more information, see this thread: https://support.mozilla.org/en-US/questions/974000

Type about:preferences#content<enter> in the address bar. Across from fonts and colors, press the Advanced button. On the bottom, turn on Allow Web Sites To Choose Their Own.

Fonts Information - Detected via Flash http://browserspy.dk/fonts-flash.php?detail=1

Sounds that you do not have a font installed that covers this Unicode range.

• https://en.wikibooks.org/wiki/Unicode/Character_reference/0000-0FFF
• https://en.wikipedia.org/wiki/Telugu_%28Unicode_block%29

Does this happen with other scripts as well?

• https://en.wikipedia.org/wiki/Brahmic_scripts

I see Pothana2000 being used to display Telugu text.

• https://www.google.com/search?q=Pothana2000
• http://www.teluguvahini.com/fonthelp