Apple Calendar repeating yearly event showing on the wrong date
I created an all day event (my dog's birthday 😁) back in 2018 and set it to repeat yearly on 6th May but for some reason in 2021 it started appearing on 5th May and the same in 2022, 2023 and beyond, so now it's wrong.
2019 and 2020 show it on the correct date 6th May. Why has it done this?
MacBook Pro 14″, macOS 13.3