What were the reasons for the frequent conflicts in the Balkans in the 19th century?

For a long time the Balkans were under the strict influence of the Ottoman Empire, but in the 19th century the Russian Empire began to poke its long nose there, because it was one of its strategic interests at that time. And the pretext for the military conflict was that people lived there from time immemorial, that they preach the Christian faith and Russia must protect them from the yoke. In addition, the Balkan countries themselves fought with the Ottoman Empire and defended their own independence. Also, England and France participated in the Balkan crisis, who were not opposed to replenishing their territories with new lands.