I would never use their proprietary clients. And when looking for software for Linux, start on flathub.org

There are Nicotine+ multiplatform and Seeker for Android.

Soulseek is entirely proprietary and scary insecure. Check the Nicotine+ documentation for an overview. They do not mention encryption or TLS anywhere, which tells us that there is no encryption. Anyone relaying or passively monitoring your internet traffic will know your username, password and what you share.

This is seriously scary as even with user accounts, known contacts etc, you basically can't trust anyone to actually be who they pretend to be. In practice it works, but that is likely because nobody cares to attack them.

The server is proprietary running whatever software and can access all your data.

And the best, they use MD5 hashes for the files afaik, which is broken. This is pretty unimportant but still interesting: the files you download are sent over an unencrypted connection and could be modified by a man-in-the-middle without you noticing. One could change the file or hide malware inside it that exploits a vulnerability etc.

Most importantly, this will just be open traffic that will be exposed to anyone who cares. You shouldnt use that IP to do ANYTHING else.

Sadly Soulseek is really good for finding stuff, still very much unbeaten.

There is aMule, recently revived. Many servers and also the decentralized Kademlia network. The UX is way worse than Soulseek, there is no Android version, the revival is heavily driven by AI... but it is pretty good, decentralized and encrypted!

I found this repo with tips for setting up aMule and some scripts.