Many sites offering "free" combolists are fronts for distributing malware. The .txt file you think you are downloading could actually be an executable script or part of a larger ransomware package designed to infect your own device.
Here is a blog post covering what these files are, how they are used, and the risks associated with them. Understanding the Risks of "Download Combo (2).txt" Files Download combo (2) txt
Use a password manager to ensure every account has a distinct, complex password. Many sites offering "free" combolists are fronts for