I hope (for your sake) that you don't have any users that can invoke their GDPR rights against you by virtue of their citizenship.
For the sake of incentivising companies to do the right thing, however, I hope you do have some EU or UK citizen users who do litigate or have their data protection authority investigate and formally punish Triplebyte, even if only to establish clear precedent here for the future.
Article 18 restriction of processing can apply here. Art. 25 "Data protection by design and by default" would seem to be relevant as well. The section I alluded to above is the latter half of 25(2), saying "In particular, such measures shall ensure that by default personal data are not made accessible without the individual’s intervention to an indefinite number of natural persons."
There's also the question of whether their consent or other grounds of processing suffice, which likely wouldn't for making anything public, but Article 25 makes it clear enough anyway this is illegal.