I can confirm this. After upgrading from Ubuntu 12.04 to 14.04 the font size (for the number of new emails) on the thunderbird icon in the unity launcher became extremely small.
$ uname -a Linux Dennis-PC 3.13.0-58-generic # 97-Ubuntu SMP Wed Jul 8 02:56:15 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux Dennis -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to unity in Ubuntu. https://bugs.launchpad.net/bugs/1446007 Title: unity launcher fonts became extremely small after update Status in Unity: New Status in unity package in Ubuntu: Confirmed Bug description: Some applications such thunderbird and unity-mail have a counter at their icon in unity launcher. In two computers with Ubuntu 14.04 the fonts of the counter became extremely small after a restart for no apparent reason. This has happened in two computers with completely different hardware and with a distance of about 1 month. Operating system: Ubuntu 14.04.2 To manage notifications about this bug go to: https://bugs.launchpad.net/unity/+bug/1446007/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp