There are a couple I have in mind. Like many techies, I am a huge fan of RSS for content distribution and XMPP for federated communication.
The really niche one I like is S-expressions as a data format and configuration in place of json, yaml, toml, etc.
I am a big fan of Plaintext formats, although I wish markdown had a few more features like tables.
I’d argue this syntax is difficult to read, especially as it scales
The syntax is only difficult to read in their example.
I fixed their example here: https://programming.dev/comment/12087783