No new hooks added in 9.3.1 Below are recently added.

    jetpack_admin_menu_use_calypso_links

    hook (filter): Whether links should point to Calypso or wp-admin.<p>Options: true - Calypso. false - wp-admin.</p>

    Source: modules/masterbar/admin-menu/class-admin-menu.php:93

    jetpack_gtag_universal_commands

    hook (filter): Allow for additional elements to be added to the Global Site Tags array.

    Source: modules/google-analytics/classes/wp-google-analytics-legacy.php:158

    jetpack_no_user_testing_mode

    hook (filter): Filters Jetpack's No User testing mode.

    Source: vendor/automattic/jetpack-status/src/class-status.php:100

    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:148

    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:517

    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:298