Anyone who likes to be scolded by their loved ones for forgetting their birthday. More pity for those who use Google Calendar, because if the contact details on Google Contacts do not have a date of birth it means that there is no birthday reminder in the calendar. For years Google Calendar also did not support manually adding birthday dates and this ends today.
For now this feature is limited to the Google Calendar app for Android. Web and iOS support will be provided in the future. The feature is also rolling out in stages starting last night and is expected to arrive to all users around October 2024.
When you press the "+" button in Google Calendar, then select Event, the displayed tag will have an additional Birthday next to Event and Task. You can add a name, date and set a color indication for more specific reminders. If this is an important feature for you, wait for this update to arrive on the device as it is distributed from the server side and not the Play Store.