What they meant is having thumbnail instead of the icon, so that you can quickly see a preview of all the files instead of having to select them one by one. This article was somewhat recently shared and it explains the whole ordeal https://jayfax.neocities.org/mediocrity/gnome-has-no-thumbna... (contains snarky language).

It’s a small(-ish) issue but people often share it as a good example of their frustration with the way Gnome is managed - the bug report has been open for years, there has been several patches proposed, but they’ve always been either rejected or ignored with no discussion. My personal (and similar) pet peeve is that typing in the window will trigger a search instead of selecting the file matching the key like in every other OS.