I believe the 87% figure was for the "new territories" that were annexed from Ukraine. 80% was overall.
BTW, Putin's popularity is 85%+ according to the Levada Center, which is a US-based polling company classified as a "foreign agent" by the Russian govt. They are funded by the National Endowment for Democracy, which is a civilian arm of the CIA (!) so I think they are reliable. They are also associated with the Univ. of Wisconsin Madison.