why does the calendar enlarge when I move the mouse over it

When using google calendar and I move the Magic Mouse 2 over the calendar it automatically enlarges which is irritating, and the only way I"ve found to get it back to normal is to go up to the "view" and change it back. How can I stop this from happening or if it does what is an easy way to get it back to normal size?

Magic Mouse 2 - Silver

Magic Mouse 2 - Silver

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