No. That is emphatically NOT entitled -- if the Traefik people have made heavy use of "open source," either practically or in marketing.

If you tout "open source" ideas in the work you do, then you can reasonably be held to the social contract that the ideas of open source originate in.

Lately (by lately I mean maybe the last 20 years or so) there's the idea of "because the open source ish company needs to pay the bills, they can completely abandon the ideas of open source."

Nah. You took from the commons, the commons has at least SOME right to ask for something back.

I never became a heavy user. All of the features that I needed were closed source so I moved on.