Hi @Francesco Casareto,
What the display language, authoring language and proofing language did Office use?
What is the system language?
I suggest you make sure 3 language are the same.
If this issue is still existed, I suggest you provide a sample word about the problem.
You can also run a repair of Office: https://support.microsoft.com/en-us/office/repair-an-office-application-7821d4b6-7c1d-4205-aa0e-a6b40c5bb88b
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