nickpick Today I've encountered an empty GrapheneOS warning. What does it mean? Is it some bug or a sign of a malware? https://i.imgur.com/k64bjll.jpeg
Hat You could try to put the language in English to see if the message appear. Other possibility less easy : check the log messages : Settings > System > View logs > 3 dot > log level Warning. You need to find the time period when the warning occurred.
nickpick I found the history of notifications. It has only one warning "App is still active". I guess it is. However, i've seen it rendered correctly. Probably, some rare bug of UI...