In yet another attempt to further monetize Windows 10, Microsoft is testing out advertisements in WordPad, the word processing app that's been built into the OS for decades. The change was spotted by Mach2 developer Rafael Rivera, and the screenshot shows six different variants for ads, all promoting the Office web apps.
The Office web apps make up the free tier of Office 365. If you move to that, the obvious goal is to turn you into a paying Office 365 customer.
This isn't the first time that Microsoft is injecting ads into apps that are built into Windows, although it's probably the first time we've seen it with apps that have been left alone for so long. The built-in Outlook Mail app started to get ads back in November 2018, assuming that you weren't already an Office 365 subscriber. Those plans were canceled.
It's likely that the ads in WordPad will never see the light of day. Even the Windows Insider Preview build that Rivera is running requires that you activate the feature using Mach2. If you're one of the few that actually uses WordPad, perhaps it would be best to see if this is ever made public before getting too upset about it.