Steps to reproduce:
(Disclaimer: Very minor UX annoyance, and not sure how it weighs against the use case of opening calculator with a "+<number>" query)
Look up any phone number with the international country code prefix without any spaces (+351XXXXXXXXX) will open up the calculator widget.
If there are no search results nothing else appears which can be more misleading (e.g. user might think search did not occur due to the assumption it was a mathematical operation)
Just seeing search results (if any) related to the phone number I looked up
Chrome, Ubuntu 20.04.4 LTS, Region: International, Connected to: EUROPE-WEST2