This overview by Josh Drummond is as good as any short explanation we’ve seen:

The short version is that there are a bunch of well-funded, right-wing, neoliberal influence and lobbying groups in New Zealand, who share links with similar groups overseas. They are ostensibly independent groups, but they coordinate their activities, share resources, trade personnel, and — when you zoom out slightly — essentially work as one large body. In fact, several of the groups officially operate under the auspices of one giant neoliberal anthill organisation, called the Atlas Network. In New Zealand, these groups — and the individuals who work in them — tend to cluster around parties like ACT, NZ First, and National. Their modus operandi is to write stultifyingly dull papers, create model legislation, get pet MPs and parties elected, and incessantly insert their messaging into the public consciousness via the media. That messaging varies from group to group, but the (almost invariable) common denominator is this:
 
They consistently oppose both climate action and recognition of indigenous rights.

Having seen extraordinary success in Australia with the triumph of the “No” vote on the Voice, these same forces look to be coming for Te Tiriti o Waitangi. Since it gained limited judicial and legislative recognition, Te Tiriti has been a bugbear for neoliberals. It represents everything they hate: an example of collective recognition and responsibility, and an admission that indigenous people do in fact have continuing inalienable rights that pre-date colonisation. Perhaps most importantly, Te Tiriti acts as a potential handbrake on the kind of unfettered property rights required for mining and fossil fuel companies to prosper. 

So it’s no surprise that the ACT Party and lobbyist enablers like Hobson’s Pledge want nothing more than to get rid of it.

From Josh Drummond’s The Bad News Letter on Substack