Can't believe "【Title tags】body text" notation is washing up here. This has to be, to describe in a William-Gibsonian description, an old Japanese practice in email titles heavily used in 2ch/5ch later became popular in Rakuten listings mimicked by Chinese listings on Amazon JP that ultimately leaked into Amazon US via machine translations.

I have never seen it done in anything other than in Japanese text, and translations of. Not sure about double bullet points, but this usage of 【】 is distinctly Japanese.

1: https://imgur.com/uKb9XI5

2: https://imgur.com/1zsxDAF