Yes, but the button is is appealing too. On https://icsdroid.bitfire.at/ the “Get it on Google Play” looks a bit lonely on the large gray square. On https://icsdroid.bitfire.at/download/ it is so far “below the fold” and in a different layout that I didn’t notice it. Hence that these buttons, with the same styling, give users of all stores in one quick look all they need to know on what stores this app is available. Understandable that you want a disclaimer since it is a build you don’t do yourself. However, it is a build that is monitored very strictly and openly, so I think you can list it proudly.