Google Indexing API - Will it harm our sites?

In the past I tried it (with Rank Math SEO). What do you think about it? What is your experience?
After 2 sites completely vanished from the SERPs, I never touched it again. But these were PAA sites and we all know what happened to these anyway

There is no point to use it.
Posts gets deindexed after couple of days.

Same situation here. All site pages get indexed and after a couple of days the site: operator didn't show all indexed pages.

But when you take any url or your site pages and put it in the search you will discover that it indexed.

There is something weired about this and i can't figure it out yet.

If you're referencing this API: https://developers.google.com/search/apis/indexing-api/v3/quickstart
It's only realistically for content that has a limited lifespan, such as live streams of events, or job postings. It does work for indexing for a lot of people, but you'll probably find that urls that only get in the index via the API will fall out again unless they get some links to back them up.

Google Indexing API works just fine with 1 to 2 posts per day.
If you have a lot of posts, delete it. I'm using it for sites with few posts that work very well

I used index api for my site for several and after some time they lost their rank

John Mueller answered this question. Min 7:02. Personally I didn't notice any improvement or worsening in the ranking while using index API.

You may find your answer here
https://www.blackhatworld.com/seo/attention-dont-use-indexing-api-let-me-show-you-why.1443689/

It is not bound to work in the same way it did before. It is because smallest of the things have undergone sea change in the world of digital marketing for the past 3 years and more. And the worst part is, more is to come!

No, bro, i did not face any issues in Google indexing API, It works fine for me.

I've been using it on all my sites for over half a year and it works perfectly.

Google Indexing API is a legitimate tool provided by Google to help website owners notify Google about new or updated content. It's designed to improve the speed and efficiency of the indexing process and should not harm your website if used correctly.

That being said, there are many factors that can affect your search engine rankings, and the use of the Google Indexing API may not necessarily be the cause of any issues you experienced with your sites disappearing from the SERPs. As you mentioned, the sites in question were PAA sites, and there could have been other factors at play that contributed to their disappearance.

If you are considering using the Google Indexing API again, it's important to ensure that your website is optimized for SEO and that you're following best practices. Additionally, it's important to monitor your search engine rankings and website performance closely after using the API to ensure that there are no negative impacts on your website.

around 45 days after submitting to google using indexing api, my sites got hit and lost ranking