Likely part of an A/B testing where they test click rates. Everything on Google's result pages is tested, font size, wording, spacing because an improvement by

Likely part of an A/B testing where they test click rates. Everything on Google's result pages is tested, font size, wording, spacing because an improvement by 0.01% is already millions of extra profit. I used to work at the competition and we did the same, often multiple tests every day.