Some steam deck owners (including myself) kept complaining about a very annoying popup that shows up when you turn on your steam deck from sleep mode in desktop mode. There's also others who complain about having a different type of popup, from KWallet as well, when they open their browsers.

I have found a solution that fixed this problem for me. If you don't care for KWallet, you probably won't have the "kwalletrc" file in your system (like i did). Some people say that you should install the KWallet app from Discover in order to create the "kwalletrc" file but this is unnecessary.

All you have to do is:
1: Open Dolphin and click the three horizontal bars in the top right corner and check the box that says "Show Hidden FIles";
2: Navigate to "/home/deck/.config/" and copy and paste to the desktop ANY file that is a text document file. For example, copy and paste the "kwinrc" into your desktop.
3: Open your "kwinrc" file in your desktop and delete every bit of text written inside of the file. Then, once everything is clear, add the following text inside the file:

[Wallet]
Enabled=false

4: Save the file and close the text document. Now rename the desktop file from "kwinrc" to "kwalletrc" and move it into the "/home/deck/.config/" directory where you grabbed "kwinrc" from.
5: Close to gaming mode and, once in gaming mode, restart your steam deck.

Your problems with KWallet should be fixed. For my case it worked, although if you want to actually USE the KWallet app or service you might have to delete the file you created (because it forces KWallet to be disabled).