Hi @D'Orazio Mario ,
As per my test, I can also reproduce this issue on my end. I find a workaround: if you use Hyperlink function, and replace "%20" with space back for URL ("%20" which is a space in the path), you could open the hyperlink normally.
=HYPERLINK("url","display text")
Back to this issue, I'm afraid the cause is that there is something wrong in the backend which we have no control of. You can create a service request in Microsoft 365 admin center to check this issue with Microsoft experts.
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