How did you add the company holiday to Teams calendar?
Can you see the company holiday in your outlook calendar?
I did a test in my environment and you can try to follow these tips to see if it works for you:
1.Sign in outlook client and make sure your account is the same as Teams client.
2.Click Calendar and create a new appointment to your Teams calendar.
3.In subject, type a name for the important date, check All day and enter a date.
4.Go to Recurrence and click Yearly, then select OK.
5.Wair for a few minutes and you will find the custom holiday sync to Teams calendar.
For more details about how to add custom holiday, please refer to:
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