TL;DR – update your ProjectLibre Desktop app to the latest version (1.9.8).
A warning is triggered when you launch an Intel-only app, and you will see it every time you launch such an app. Launching a recently used Intel app again won't trigger it, but if enough time has passed then you'll see the warning again for that app. For example, I last used the SynologyAssistant app to check on my NAS over a month ago, and launching it generated the banner message.
That warning means that the app in question will stop running on macOS 28, assuming you upgrade to it when it comes out in the fall of 2027 (just under a year from now). In the meantime, ProjectLibre Desktop will keep working but you'll see the occasional nag. You should be prompted to install Rosetta 2 if it's needed.
If you don't see the prompt, you can install Rosetta 2 using Terminal. Apple provides instructions for that HERE.
To avoid this issue you need to run only Universal or Apple Silicon apps. For apps that are Intel only, contact the developers and push them to release updated versions of their apps (but keep in mind that they have over a year before their apps stop working on macOS).
In the case of ProjectLibre Desktop, v1.9.8 runs natively on Apple Silicon (M-series Macs), so update to that version and you will not see the warning nor will you need Rosetta 2 to run the app.
To see which of your other apps are Intel and thus need to be updated or they won't run on macOS 28 (Fall 2027), hold the Option key and click the Apple menu, then select System Information (the top item). Select Applications in the Software section of the sidebar, then click on the Kind column header to sort them.
Some apps aren't readily identifiable by the name, but when you select that app you will get more info. For example, 'commandFilter' is a component of the Epson printer drivers. Apps like that can be safely deleted.
Here's what Apple has to say about updating your apps:
Learn how to update Intel-based apps for Apple silicon - Apple Support
