And in some of those cases GPL wasn't enough to prevent it. Niche end user utilities, where original is available for free have little room for monetization. And in many cases existing users are already choosing the open source option despite the existence of commercial solutions, or where it's too niche for commercial solutions to exist.
Only thing that comes to my mind is VScode with all the AI craze. But that doesn't quite fit the pattern neither is the Microsoft underdog, nor it's clear that any of AI based editors derived from VScode will survive by themselves long term.
There are also occasional grifters trying to sell open source software with little long term impact.
VSCode is a proprietary fork of code-oss, the product located at https://github.com/microsoft/vscode. It might not be an example that you're looking for though.