"Google will discontinue third-party niche search engine access to full-web search" would be far clearer.

Given that the title supplied is effectively editorialised, and the original article's title is effectively content-free ("Updates to our Web Search Products & Programmable Search Engine Capabilities"), my rewording would be at least as fair.

HN's policy is to try to use text from the article itself where the article title is clickbait, sensational, vague, etc., however. I suspect Google's blog authors are aware of this, and they've carefully avoided any readily-extracted clear statements, though I'll take a stab...

Here's the most direct 'graph from TFA:

Custom Search JSON API: Vertex AI Search is a favorable alternative for up to 50 domains. Alternatively, if your use case necessitates full web search, contact us to express your interest in and get more information about our full web search solution. Your transition to an alternative solution needs to be completed by January 1, 2027.

We can get a clearer, 80-character head that's somewhat faithful to that with:

"Google Search API alternative Vertex AI Search limited to 50 domains" (70 chars).

That's still pretty loosely adherent, though it (mostly) uses words from the original article. I'm suggesting it to mods via email at [email protected]; others may wish to suggest their own formulations.