Let's get a baseline for comparison. For example, how many climate tech startups, or tech startups in general, are "likely junk"? That would give us some helpful context.
Junk startups don't cause much harm to the outside world. In contrast, selling junk carbon offsets is basically fraud, you're selling an environmental impact that just isn't there.
Giving junk a pass under normal circumstances may be what is causing much of this greenwashing. It speaks to the overall culture of startups.
If this 78% figure is consistent with the figures of tech startups in general, that would suggest a connection.
And that's only one reason why I'd like a baseline; there are many more. Throwing out a single percentage without comparisons for context is just plain bad statistics. It is not meant to inform, merely to persuade.