When you press “tweet” on Twitter you give Twitter consent to display your words on their website, unlike the compilers which will display it without consent
You grant [them] a worldwide, non-exclusive, royalty-free license (with the right to sublicense) to use, copy, reproduce, process, adapt, modify, publish, transmit, display and distribute such Content in any and all media or distribution methods (now known or later developed). This license authorizes us to make your Content available to the rest of the world and to let others do the same.
https://twitter.com/en/tos Emphasis mine.
The permission you give Twitter also extends to thread compiler apps, to whatever extent Twitter feels like sublicensing.
But yes, if you're writing on twitter, you are giving them permission to use your content.
But does Twitter sublicense? Why would they want to support usage of a third party service?