What’s its uptime? A lot of Electron apps—even ones that use minimal local JS, serving mostly as a webview—accrue base overhead as you use them, then keep it around even when you close their main window (and thus release their main Chromium-side render context), as long as the process stays alive. They’re caching stuff (like, as I said, rendered font glyphs, or network responses.)
I have a copy of Slack running that’s using 2GB right now, with no window open.
They might call this "caching" but it's still a memory leak. Over time, the application consumes increasing amounts of a finite global resource while not appreciably advancing its own progress, and negatively affecting the whole system. That's a memory leak.
The solution is for operating systems to inject deliberate back pressure on memory allocations for user-selectable applications to stop them from behaving this way. "No memory for you. Try mallocing smaller chunk. Maybe I grant; maybe I don't. Maybe I just kill -9 you if you bug me too much." This is exactly how I wish my OS would treat web browsers.
I have a copy of Slack running that’s using 2GB right now, with no window open.