I have 4 IBS-TH1 Plus and one IBS-M1 (rev2) gateway in a fixed local constellation in my apartment. The sensors are logging data by themselves plus they are logged from IBS-M1 to the cloud. Since the start of that configuration I notice that intermittently for all sensors, the historical data of past days gets lost and is no more retrievable. This happens for each senor individually from time to time and is not linked to any external action. No change of local constellation of sensors and gateway is done. No change of sensor configuration in the IBS-M1 is done either.
Usually I export each day the past day to CSV to make sure I have the complete history of records. Today again the past days of one of my sensors is lost 
The button to export data and the one to delete all historic data are quite close, but I am sure that I do not delete historical data by accident, as there is a safeguarding confirmation for this action.
You should issue a similar warning/confirmation on all occasions where this might happen.
The Engbird app for direct programming the device and to retrieve the logged data from the IBS-TH1 Plus warns when you change the interval, that data is deleted.
The Inkbird Pro app does not warn on this occasion, however the historic data is deleted nevertheless when changing the interval. Since data a logged to the cloud, why delete them there when you alter the interval to log new data? I understand that the internal buffer of the IBS-M1 needs to be cleared but I would prefer if you keep the historic data in the cloud in any case and merge the records there after changing the interval time.