Why are parts of application in a different language?

As you can see in the screenshot there are a couple of parts of the F-Droid application page in F-Droid that are in a different language. This isn't actually the first time I have seen this and is not limited to the F-Droid application. Currently it's just this one, but in the past I have had more apps than not displaying some or all of their content in a different language despite my phone being configured for English.