Ethics are not obligations, they are moral principles. Not having principles doesn't send you to prison that is why it isn't law. It makes you lose moral credit though.
However, almost every open source license actually DOES warn that support may end. See the warranty clause.
With open source it does. If an indie open sources and get a baby or lose interest, it is understood as fair to suddenly stop maintenance.
When a company surfs on the open source wave to get contributions, grow penetration, then smoothly slows maintenance and announces to get a license, that's gaming the open source community.
See the numerous cases of popular open source repo where the parent or new parent company took over to gain the user base without any respect for the maintenance if not development aspect: community fork and take over the community.
Mariadb, a more recent illustrative example of that is the hashicorp drama that occured when investors decided it was time to gear towards profit at the detriment of the community that largely contributed to the tools.
Claiming that you’re entitled to free R&D forever because someone once gave you something of value seems like a great way to ensure that nobody does that again. You got over a decade of development by a skilled team, it’s not exactly beyond the pale that the business climate has changed since then.