Observation 2508290: MOZHAYETS 4 (27939)

Regarding Observation 2508290

satnogs https://db.satnogs.org/satellite/27939/ shows only CW beacon, so what could this have been on that frequency ?

Interesting catch! The signal tracks with the expected Doppler shifts for RS22 (no “bending”) so we can be confident that the signal is coming from RS22. DK3WN.info has several posts with a similar signal, a phase-modulated type known as DOKA. Here’s an example. And in this post we see some discussion of telemetry format. A list post from 2004(!) suggests that RS22 transmits DOKA when in range of its ground station in St Petersburg.