Summarizing this post, for observations scheduled between Dec 13, 2022 (SatNOGS Network release v1.98) and Dec 21, 2022 (SatNOGS Network release v1.101) the correction for the known frequency drift of a transmitter was not applied when scheduling.
This resulted in observations to show a frequency shift in the waterfall for those transmitters that have such a drift. Example: Observation #6909130
Since Dec 21, 2022, all newly scheduled observations do have the frequency drift correction correctly applied again.
For more details, including info on new features like the option to manually select the frequency when scheduling observations of Transponders, see the latest SatNOGS Network release thread.