In all cases, unless you have made customizations, data is indexed from Magento indexers to Algolia. You can check these indexers using this guide, and you can manage the indexers in your Magento admin by going to Tools > Index Management. Here is a screenshot of what these indexers look like:
Assuming these are up to date, you should then check the Algolia indexers as well:
If you are adding data, and nothing is changing in the index configuration for your Magento indexers, this indicates that no updates are being made in your data. You should then debug your Magento indexers and reach out to Magento support as needed.
If the data is added to the Algolia indexers and you are still not seeing the updates made, the following resources can help troubleshoot issues with the Algolia indexing queue: