It’s very easy to do once you know what you’re doing. This took me like 2 minutes to throw together. I gave the text a background and everything so it should be easily visible no matter the picture’s background color.

My problem with your watermark is it’s basically worthless to anyone who doesn’t already know what Lemmy is. Unless I’ve somehow missed it, nowhere on the watermark does it actually mention Lemmy. A logo by itself is completely worthless if you’re not well known. You really ought to add ‘join-lemmy.org’ in there under the logo imo, which would make it infinitely more useful.