That is supposed to be a Saturated NaCl solution that gives 75% RH, but this time SHT85 shows 77.7%, So it might be not perfect, also some AHT25 sensors got some weird numbers.
Humidity
Measurement for time 23:12
Average measurement for time 23:12
Humidity trend
Temperature
Measurement for time 23:12
Average measurement for time 23:12
Temperature trend