There are many parcels. The private sign you showed is only for the overgrown passage with high grasses near the fence on parcels 907B 907C. You've put  the track as private though which is on another parcel 927 and deleted the rest of the way going through parcels 926A and 927. One private sign for a parcel is not necessarily one for the others. 

Apparently people pass on these parcels as shown on Strava activities one only 4 days before you deleted it https://www.strava.com/activities/10526379143 and in 2023 https://www.strava.com/activities/9038368641 ,
https://www.strava.com/activities/9038199083

Where is the evidence that these are private and did you contact Cadastre of Belgium?