I agree that it doesn't look good. Unfortunately, I do not believe that there is a way to change it. Its what they do when they are fundraising for projects, and should go away soon. It also should go away if you donate, but that's your choice.

Have a great day!

See my second reply here:

• [/questions/1038807#answer-670671] Who took a pee on Foxfire Start page; how get rid of yellow color?

Mozilla shows snippets on the about:home page to run different campaigns and that changes regularly.

If you prefer not to see snippets on the about:home page or if there are problems with a snippet then you can set the browser.aboutHomeSnippets.updateUrl pref to an empty string on the about:config page. Delete the storage\persistent\moz-safe-about+home folder in the Firefox profile folder with Firefox closed ("3-bar" Firefox menu button > Exit/Quit) to remove snippets stored in IndexedDB and make Firefox use a default snippet set. You can reset the browser.aboutHomeSnippets.updateUrl pref via the right-click context menu to the default value to re-enable the snippets and make Firefox recreate the moz-safe-about+home folder. Close and restart Firefox after changing the value of the browser.aboutHomeSnippets.updateUrl pref.