Some high humidity test results
at RH ~75%
https://wiki.liutyi.info/display/ARDUINO/Test+5+v5+saturated+salt+solution
So the RH measurements are:
AHT10, HDC1080, AM2320 - above expected
HTU21d, BME280, BME680 - below expected
Si7021, SHT3x, most SHT2x, SHT85 - expected
t measurements (using SHT85 as a reference, since no other precision thermometers available)
BME280, BME680 - Above expected