I needed to reinstall Firefox on this computer, so I started up Chrome to download the latest version and it blocked the download as unsafe! I had to manually tell it to download anyway.
Fuck Chrome. I’m glad I only used it to download one file and went back to Firefox.
You have disabled Safe Browsing. That prevents files from being checked for malware, so all downloads are blocked by default (nothing to do with Firefox). As you noted, you can override the warning to download anyway, but it is an extra step to try to reduce the chance of someone accidentally running a malicious program.