Solution for accessing Settings in Xiaomi Poco F3, for those of us who suffer from it. I don't know if it will be resolved directly in an update.
You have to activate the Services & Feedback apk again, which is the one that gives the failure if it is deactivated.
For this you need the PC application "Xiaomi ADB / Fastbbot Tools" and this in turn, to work, you need Java on the PC.
1-. On the mobile, create a "Access Settings" Widget and choose "About phone", enter the created Widget and activate the developer options by pressing several times on MIUI Version.
2-. Create another Widget from "Access Settings" and choose "System", enter the created Widget and go to Development Options and activate USB Debugging.
3-. Open the Xiaomi ADB / Fastbbot Tools application on the PC and connect the phone, give it the permissions it requests.
4-. The application detects the phone and two tabs appear at the top, the first one has the apk installed on the phone and the second one has the non-activated ones, click on that one and look for Services & Feedback, mark it and click on the bottom to install.
Once this is done, there is already access to the Settings. I hope it helps you, if there is a simpler way, I have no idea.