No new hooks added in 9.1 Below are recently added.

    jetpack_content_options_featured_image_exclude_cpt

    hook (filter): Allow featured images to be displayed at all times for specific CPTs.

    Source: modules/theme-tools/content-options/featured-images.php:17

    jetpack_recaptcha_valid_hostnames

    hook (filter): Allow other valid hostnames.<p>This can be useful in cases where the token hostname is expected to be different from the get_home_url (ex. AMP recaptcha token contains a different hostname)</p>

    Source: modules/sharedaddy/recaptcha.php:147

    jetpack_widget_visibility_get_pages

    hook (filter): Filters the retrieved list of pages.

    Source: modules/widget-visibility/widget-conditions.php:293

    jetpack_widget_visibility_max_number_tags

    hook (filter): Specific a maximum number of tags to query for the Widget visibility UI.

    Source: modules/widget-visibility/widget-conditions.php:116

    jetpack_widget_visibility_max_number_categories

    hook (filter): Specific a maximum number of categories to query for the Widget visibility UI.

    Source: modules/widget-visibility/widget-conditions.php:63

    jetpack_is_frontend

    hook (filter): Filter whether the current request is for accessing the frontend.

    Source: functions.global.php:518

    jetpack_instagram_embed_token

    hook (filter): Filters the Instagram embed token that is used for querying the Facebook API.<p>When this token is set, requests are not proxied through the WordPress.com API. Instead, a request is made directly to the Facebook API to query for information about the embed which should provide a performance benefit.</p>

    Source: modules/shortcodes/instagram.php:216

    jetpack_amp_infinite_next_page_data

    hook (filter): The next page settings.<p>An array containing:</p> <ul> <li>title => The title to be featured on the browser tab.</li> <li>url => The URL of next page.</li> <li>image => The image URL. A required AMP setting, not in use currently. Themes are welcome to leverage.</li> </ul>

    Source: modules/infinite-scroll/infinity.php:1981

    jetpack_amp_infinite_older_posts

    hook (filter): AMP infinite scroll older posts markup.

    Source: modules/infinite-scroll/infinity.php:1927

    jetpack_amp_infinite_separator

    hook (filter): AMP infinite scroll separator.

    Source: modules/infinite-scroll/infinity.php:1909