That is because speed-test is not installed. The npm command says Show me all the places agent-base is used and what version it is. If you look at the earlier post it had
npm list agent-base
node-red-project@0.0.1 /home/me/.node-red
├─┬ node-red-contrib-speed-test@0.1.2
│ └─┬ speedtest-net@1.6.2
│ ├─┬ http-proxy-agent@2.1.0
│ │ └── agent-base@4.3.0
│ └─┬ https-proxy-agent@3.0.1
│ └── agent-base@4.3.0
└─┬ node-red-contrib-tts-ultimate@2.0.5
├─┬ @google-cloud/text-to-speech@4.2.2
│ └─┬ google-gax@3.6.1
│ └─┬ google-auth-library@8.9.0
│ └─┬ gaxios@5.1.3
│ └─┬ https-proxy-agent@5.0.1
│ └── agent-base@6.0.2 deduped
└─┬ microsoft-cognitiveservices-speech-sdk@1.29.0
├── agent-base@6.0.2
└─┬ https-proxy-agent@4.0.0
└── agent-base@5.1.1
So you can see that agent-base 4.3.0 is used by http-proxy-agent which is used by speedtest.net which is used by node-red-contrib-speed-test.
Now you no longer have speed-test installed the early version of agent base is not used.