Is it considered allowed to observe birthdays since I have noticed Sunni scholars disapproving of it on social media, while Shia individuals celebrate the birthdays of the Imams and Lady Fatima (a)?
Bismihi ta'ala
For Ahlul Bayt (a.s.), it would definitely be mustahab and highly recommended to celebrate their birthdays.
As for our birthdays, it would be permissible, as long as it does not entail any haram act or practise.
And Allah knows best