What causes the Magic Mouse cursor to enlarge paragraph size on specific websites?

I was on a website and accidentally clicked on my magic mouse 2 for a few seconds (I think this is what caused it). After that my cursor which transforms into a vertical line when hovered over text (normal behavior of the cursor) enlarged to the size of the whole paragraph I was hovering. It adjusts itself to the size of the paragraph (if there are 2 lines of text, it’s over those 2 lines, if it’s 4 lines, it covers all 4). I think the maximum of covered lines is 4 or 5 and it’s just on this website. Any other tab I open is normal. I can not reload the tab or open the website in another one, it’s still enabled. I want to know, what function on the mouse caused it, because I’m not able to return to the normal settings by clicking, holding, etc.

[Re-Titled by Moderator]