Maybe strangely, this has happened to me at least once in every place I've lived long term. Seems somewhat common with big selloffs for new roads and houses or when new management comes in and cracks down on previously tolerated paths through private land.
I grew up in a small east coast town that had a bunch of nice wooded trails nearby. These were mostly on land owned by the township but weren't official parks or anything and the trails were just maintained through frequent use. A couple segments of these have been converted to official (but tiny and disconnected) parks and trails over the past 40 years, but the large majority was sold off for housing or had roads built over them.
In the city I went to for college, we had a large park that was cut in half by infrequently used freight tracks. There were some nice wide trails connecting both sides of the park that were well maintained enough to think were official, but near the end of my last year of college whoever owned the rail line decided they weren't happy about this and started putting up barriers and even got the police to stake out the area and hassle anyone still trying to cross about trespassing. The nearest official place to cross was a few miles away from the park, so this only temporarily stopped anyone.
I had a fairly similar experience in the next city I lived in. We had a big park and cemetery bumped up next to each other. And while the cemetery had no problem with runners using their paths, there was only one official entrance that was pretty out of the way. So people cut a bunch of holes in the fence and maintained quite wide trails connecting through them. These were around for at least a decade before the cemetery owners decided to block them all up one day.
I currently live in the UK with access to a very extensive network of footpaths and commons. This time the paths I have in mind are public right of way and land owners are required to maintain them and give access, but of course this doesn't stop some from illegally closing them and wrongfully putting up private land signs. There are official channels for reporting these, but they're usually slow to act and very dependent on the mood of the local council. There are also some commons that are public access but completely surrounded by private land, and it can be pretty hit or miss whether owners allow people to cut through their land to access them.