After updating to KDE Plasma 6 and Dolphin 24.xx.xx my sidebar icons are not the ones that are supposed be (Symbolic Icons). I use Arch linux and I updated a long time ago and this problem appeared but I thought it was a bug but it doesn’t seem to be fixed in the latest version of KDE Plasma anyways.
So, how I can fix this? I need to delete some configuration files for dolphin so I can make Dolphin look like it was before?
As @Balder said. I tried setting my Global Theme from Breeze Dark (Which I use) to either Breeze and Breeze Twilight and those 2 themes show the symbolic icons in Dolphin.
If I change back to Breeze Dark the icons are back to the ones that I showed in the OP picture.