Screenshot, of the previous toot in this thread, with the little dinky, low-contrast connection line to the previous toot circled in red.
https://media.universeodon.com/media_attachments/files/111/531/451/351/272/504/original/7b808484d1c1174b.jpg
Like on the app I'm using on my phone, you get no indication at all in the stream that it was boosted to that it is part of a larger thread. If you click through to it, this is all you get:
GNU social JP is a social network, courtesy of GNU social JP管理人. It runs on GNU social, version 2.0.2-dev, available under the GNU Affero General Public License.
All GNU social JP content and data are available under the Creative Commons Attribution 3.0 license.