A European visiting the US and interacting with an American business does so under the protection of US law, not EU law. This is complicated in the case of Facebook and google because they also do business in Europe, so European courts can fine their European branch offices. But Triplebyte has no such EU presence that the European courts could pursue. And they don’t advertise European jobs. I suspect an EU citizen interacts with triplebyte legally the same way they would if they went to a cafe in SF while on vacation.
The opposite would be crazy. If triplebyte can be fined by the EU, that would also mean the government of Australia or China or Russia could arbitrarily levy fines against any US company if one of their citizens interacted with a US website one time. And everyone would put geo blocks on their websites to protect from liability.