One of the worst things about being a Linux user is that you have to deal with Linux users from time to time. Like the time an extension author had to quit due to being shit on by users.
I wasn't able to screenshot it, but my Just Perfection app gave me a notification as well.
I strongly believe that application authors should be the priority for the Linux desktop. This has to be sustainable. Look at how annoying it is to put together my donation page for Bluefin.
That pop up worked amazing for KDE, bravo! However we have to think of a "version 2".
One thing I love to do: when I went through a purging of my subscriptions I use the money saved to sponsor someone, even if it's only a couple of bucks. That's right, I quit proprietary services not for the Freedom, but for the Sustainability. It's an easy deal for the end user, if you want better Free Software, invest in it. That should be baked in.
I hate managing all these donations. I feel bad when I rotate someone out, or focus on something else. I at least try to commit to 6 months. I wish I could just toss some cash into a pool. If this magically existed, Bluefin would look like this:

I'm aware the menu needs copyediting and some more thought on what should be in there. But for the sake of the idea let's say I put a Donations entry here. This connects to a thing. (Yes, someone would have to build the backend). Put a little red heart in there and everything. Then let me go to whatever platform and spend $X a month.
And since Flathub is in the picture, we have access to the donation metadata. Then, the infra people take a cut to keep the thing alive (Flathub, Distro, GNOME/KDE Foundation etc.). But the bulk of it would go to the application developers to the applications I actually have installed! Just measure which apps I use the most and mix it up to keep fresh apps coming in.
I'll always pick dedicated applications to donate too, but a nice "slush fund" I could toss cash at to just spread the wealth would be great.
Then when a new app is trending, wouldn't it feel good to see the author's donations grow with it!
There needs to be guidance for application developers on this because you know some distros are going to add a popups because KDE did it. I would (lol). We could really help skip a lot of angst if we just collectively figured out the ratios and made recommendations.
Show little progress meters in an app, maybe some slider to adjust pay ratios, that kind of thing. ElementaryOS does something like this.
But the point would be a consistent UX, the desktops can figure out a classy way to remind the user using their own design language.
We could even highlight large important items that need to be funded in order to unlock app developers. For example we would prioritize Flatpak Portal and general Flatpak maintenance. Those have to be in good shape so app developers can succeed.
And you know what, if it helps fund another Linux-friendly engineer at Framework or another OEM, give me that option too. 😄