We are doing this as a courtesy to the free user and is not something I would spend more time building (our resources should go building features that paid users want).
Vlad The post starts with "It will be quite annoying for users testing the service with $5", which would be the "standard" plan, right? I don't see how you concluded from there that this is a feature request for free users 🤔.
This said, I am a paid user and I agree with the request: I have seen many people online saying "I am ready to pay for my search engine, but not $25". You can try to convince them that they probably won't have to pay $25, or you can offer them this feature: "Just set your limit to $10 (or whatever you are willing to pay) and a fallback. After your monthly credit is used, Kagi will automatically redirect all your searches to your fallback until the end of the month".
Maybe that would help people get started, and for those who would need the "ultimate" plan but can't afford it, it allows them to support you up to the amount of their choice. I am maybe naive, but I believe that quite a few users try Kagi not because it's the best, but because they want to support your model (at least it is my case). Maybe you should not under-estimate that.