Sounds like your RedMi really messed up their OS if they don’t use your default browser.

You can disable Chrome, but not uninstall it, because Chrome is what backs the modern WebViews used in all kinds of apps. Before, we used to have this separated (a WebView and a browser, both taking up half a gigabyte of storage), and before that we had the even worse situation of “WebView implementation is built by the manufacturer when the phone was released and becomes a malware vector the day the first security update comes out”. The current implementation saves a lot of storage space.

That said, some apps opt into “custom tabs”, which are Chrome/Firefox tabs that behave like they’re part of their parent app. If you’re running into those, you can either try disabling them (usually a setting) or start using apps that don’t exhibit this behaviour. These tabs don’t appear when opening a web page normally, they’re opt-in features the developer needs to specifically call out to. I’m not sure if any browsers beside Chrome and Firefox implement the protocol, but you can ask your browse vendor about Custom Tab support if you want to be sure.

For the bloatware (these cheap phones come packed with that shit), I recommend taking a backup and looking at the common debloater tools (there’s one I used that works straight from the web browser through the magic of WebUSB) to disable apps. You won’t be getting any storage space back because that’s not how storage works on Android phones, but you’ll save yourself some battery life and frustration by disabling bloatware apps. That said, don’t just disable anything labeled as “Google” or you’ll have to reset to factory settings when you inevitably disable some system service.

Your specific issues don’t seem to have much to do with Google, more with RedMi and the apps you’re using.