Could the 'unknown source error' with a 403 response actually relate to a compromised or modified version of Smart Tube Next?

While the 'unknown source error' combined with a 403 typically points to content access denial, there's a possibility that if Smart Tube Next was downloaded from an untrusted or modified 'unknown source' (i.e., not its official GitHub), the installed version might be outdated, corrupted, or contain malicious code. Such a version could fail to properly authenticate with YouTube's servers, leading to a 403 Forbidden response. Always ensure you are using the official, unmodified app version.