BME280 measurement error

I observe with the sensor BME280 with reference to the humidity a behavior that I do not understand. For years, a curve was always displayed, now there are periods in which the value falls to zero, remains there for a while and then displays “normal” again. Now (currently) this is happening again.

verify www.reiair.aqi.eco location Mancha Blanca

Is there any similar experience and maybe a solution ?

I would say oxydation of the pins.
Try to wash them with contact fluid.