I don’t have a source but this is based on my membership in the Kagi Discord server. Kagi search has decided to allow people to opt out of Brave results being included in the results and may asking Brave for free API access so that they aren’t being supported. I’m still unsure about whether I’ll resubscribe to Kagi. I might give Startpage a run for a bit.
Kagi is pretty transparent in their publicly-readable feedback site. This is the thread that kicked off the conversation. Warning: it’s a shitshow. https://kagifeedback.org/d/2808-reconsider-your-partnership-with-brave
Vlad is the founder of Kagi so you might want to focus on his replies.
There is further discussion in the Discord, which is not publicly-readable. I believe the “if we got Brave access for free” question was simply to get to the heart of users’ complaints — whether they are purely financial or something deeper.