It doesn't sound like what is happening here, but I don't think you should be able to block development on land you donated indefinitely.
You don't pay taxes on land in current use, but, if you or whomever you sold the land to, wants to build on it, they have to pay the back taxes first. It's a great for conservation.
I also don't see how this behavior is in the public good, even if the donor has some ulterior motive, governments are free to reject donations
https://www.washingtonpost.com/nation/2024/06/24/corner-cros...
https://en.wikipedia.org/wiki/Rule_against_perpetuities
In this case, the farmer should have talked to a lawyer first. There are ways to set thing up to prevent misuse.
While I'm sure that's happened once or twice and serves as great fodder to get people of a certain ideological bent riled up, for the most part nobody is giving government land that's worth a shit. They're doing it to land that's effectively unusable due to regulation. Like if you own a strip that's a many acre 30ft wide along a steep river bank plus some space for a house (the lot layout could be the result of an old railroad or industrial thing) you gain literally nothing being on the hook for all that and you can't use it. That sort of thing is the typical case in which these sorts of things are invoked. It's more of a "well if you jerks care so much about what I do with it you can have it" type deal than a tax dodge.
On land you contractually purchased with the condition that development be blocked indefinitely? Then why sign the contract? If they wanted a time limit, they could have put it in the contract, or not signed the contract.