Please run php maintenance/updateCollation.php --force on all Russian-language projects using uca-ru collation. For some reason the sortkeys generated before January 2015 and those generated later use a different format, resulting in incorrect ordering (see T88088: Incorrect sorting in categories on Russian-language projects).
- ruwiki
- ruwikibooks
- ruwikinews
- ruwikiquote
- ruwikisource
- ruwikiversity
- ruwikivoyage
- ruwiktionary
I think we're planning to upgrade our version of ICU soon, which will require running this script on these wikis anyway (T86096), so if that's happening within next few weeks, we could probably do it only once later.