Since these are third-party ISOs, there is no guarantee that the developer hasn't included malicious code. Furthermore, because Microsoft no longer issues new security patches, the OS is inherently more vulnerable to modern exploits than Windows 10 or 11.
Revive that old PC with Linux Mint Xfce or Windows 10 LTSC (which is supported until 2027). If you must use Windows 8.1, stick to the official Microsoft ISO with a paid antivirus—skip the "Lite 2023" mod. windows 81 pro lite 2023
First, a hard truth: