Fresh water level indicator

[bri]

Fresh water level indicator not working correctly.when filling,it reads 25,50,75,then 100%>then without any use immediately goes down to 50,having discharged water via overflow.is this the norm on a benimar benivan 122 2019??

 

[Two on Tour]

2 posts, same problem, different wording ?

 

[Andacami]

Double post. Responses are building here: https://www.motorhomefun.co.uk/forum/threads/freshwater-tank-level.242682/