If you saw birthdays appearing in your main Google Calendar, then you can read more about it here, it is a new feature of Google Calendar:
I.e.
Google has now removed the separate birthdays calendar and instead put
the birthdays into the main calendar. I think it would have been better
to keep it separate but Google has changed it this way now.
Anyway,
they have also added a field "eventType" to see which events are
birthdays and which are normal events. With the next update there will be a setting "Settings > Display and Use > General > Show Google Calendar birthdays" that you can turn off to hide these birthdays. Or you can keep it turned on and use "Background Color Calendar" in the next line to set the color for the birthdays.
However, this will only work for birthdays that were downloaded after you have installed this new CalenGoo update. Because only then CalenGoo will download the "eventType" of the changed events. So to let CalenGoo display all birthdays correctly you have to re-download your main calendar, e.g. by setting it to "Forced redownload once, visible" under "Settings > Visibility/Download" and then syncing once. But I would recommend creating a backup under "Settings > Backups > Automatic backups > Backup now" before doing this.
Please don't hesitate to contact me again if you have further questions!
Kind regards
Dominique