Symbols / Dingbats cannot be displayed
Symbols / Dingbats such as U+2715 (✕) [1] and U+2304 (⌄) [2] cannot be displayed in Tor Browser.
I guess Tor Browser's bundled fonts do not have those glyphs and as such users will see boxes with code point inside ("tofu").
[1] Used in Wikipedia's donation dialog (close button)
[2] Used in XE.com (down arrow)