When you launch a new window (e.g., Ctrl+n), unlike when you launch a new tab (e.g., Ctrl+t), Firefox should display your home page. Is your home page related to Microsoft or Xbox? If not, it's hard to explain why there are Xbox tips there unless you have an add-on that has taken over the page. Could you check your home page setting here:

• Windows: "3-bar" menu button (or Tools menu) > Options
• Mac: "3-bar" menu button (or Firefox menu) > Preferences
• Linux: "3-bar" menu button (or Edit menu) > Preferences
• Any system: type or paste about:preferences into the address bar and press Enter/Return to load it

In the left column, click Home

Then on the right side, you should find the address of your home page and an indication of whether an add-on is controlling it.

If your home page is the built-in Firefox Home (Default) page, use, the settings further down the tab to show/hide different sections of the page and see whether that fixes the problem.

And finally, take a hard look at your add-ons. You can view, disable, and often remove unwanted or unknown extensions on the Add-ons page. Either:

• Ctrl+Shift+a (Mac: Command+Shift+a)
• "3-bar" menu button (or Tools menu) > Add-ons
• type or paste about:addons in the address bar and press Enter/Return

In the left column of the Add-ons page, click Extensions.

Then cast a critical eye over the list on the right side. Any extensions Firefox installs for built-in features are hidden from this page, so everything listed here is your choice (and your responsibility) to manage. Anything suspicious or that you just do not remember installing or why? If in doubt, disable (or remove).

Any improvement?

In addition to the above :

The latest Windows update may have 'left you a surprise' : the Xbox ....

Please see :

https://win10faq.com/how-to-remove-the-xbox-app-from-windows-10/