Thanks for all your answers.

@khaled0111: Yes @Pmalek is correct. The reason for the German "[imported, nur lesen]" in the screenshot is that it's a watch-only wallet, that is, I imported the address without providing the corresponding private key.

@Abdussamad, @nc50lc: I just created a Github issue. See here: https://github.com/spesmilo/electrum/issues/8067