Russia Ukraine war, page-209702

Sudden no. Over 3 months of protests is not sudden. You might want to check the definition if sudden again

Violent yes. Though itv was the government violence against protestors, not the other way around as you dishonestly imply.

Illegal yes. The situation Putins puppet CREATED after he abandoned the presidency VOLUNTARILY was illegal.

There was no overthrow. There was no taking of power, free and fair elections were held months after Putins puppet abandoned the presidency.

There was no coup.