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.
While I agree that it’s somewhat bad that there is no distinction between lossless and lossy jxl in the file extension, I think it’s really not a big deal compared to the present situation with jpg/png.
The reason being that if you download a png file you have no idea if its been converted from jpg, if it’s a screenshot of a jpg, or if it’s been subjected to lossy reencoding by a tool or a website upload process.
The only thing you can really do to try and see if the file you’ve downloaded has suffered encoding loss is to do an image search on it and see if there are any better quality versions out there. You’d do the exact same thing with a jxl file.