Russia was previously allied with Prussia (Russo-Prussian Alliance).
However, with time, Russia's attention was increasingly drawn towards the south, and the Ottoman Empire.
Advocated by Grigory Potemkin, the new direction reduced the strategic value of Prussia as an ally to Russia and made Austria once again a more appealing candidate.
The Russo-Prussian Alliance was once again extended in 1777, but at the imperial court in Saint Petersburg, Nikita Ivanovich Panin's pro-Prussian faction had its influence eclipsed by the Potemkin's pro-Austrian faction.
[1] After the death of Maria Theresa of Austria, Joseph II of Austria wanted to improve relations with Russia, and secret negotiations begun in early 1781 and resulted in an Austro-Russian alliance being formed around May and June 1781.