Macbook Pro - OSx 10.15.7 - no @ symbol possible

On my Macbook Pro, I cannot type an @ symbol in various input fields. For example in the email Id input field for customer creation (the popup).
What can I do?

I can copy paste it from somewhere else. In some input fields, I can enter an @ symbol, f.e. in item name field.

This has been reported here:

https://github.com/frappe/frappe/issues/11472