I have an alternative Link Browser, but I dont know why (maybe because an extension?) how do I deactivate it or enable the default one?

I couldn't find someone that also has this Link window, so maybe if anyone ever had this one and knows where it's coming from.
If you have created and registered a custom rte.yaml for your extension, you have to import the plugins.yaml from the core to get the expected link browser.
It should look like this: