I don’t understand this take, if Google/AWS/Microsoft decide to host your service and some vulnerabilities are discovered then you got free Security Research done, your product would either have remained vulnerable or someone else would have filed the same bug.
You own the code so you can decide only certain people can commit PRs and can choose to close any feature requests issues.
If one of the cloud providers decided to use your product it’s because they deemed it reasonable as is or they can fork / contribute upstream.
That is what OSS is, by definition.
Hell you can post the code with a license like MIT and then never touch it again, and if someone else can monitise that code kudos to them.
If you are an existing company and open sourced your code, Facebook/react, then you presumably already make enough money to support development yourself or intend to stop development.
If you open source code that is your core business and somebody “steals your lunch” your learnt an important lesson and hopefully won’t make the same mistake twice. If you then decide to relicense and the community abandons you and causes uproar on the internet you are reaping the rewards of your actions, accept them.