VBEinc Clickteam has replaced the entire UI Library because the old one was abandoned many years ago by Microsoft.
It was the only way to allow customization and dark mode.
They also change this to allow DPI Aware, replacing all toolbar icons with SVG (scalable vector graphics), meaning it won't get blurry or pixelated when people use it on high/low res monitors with different Windows scaling.
Edit: Try this skin... Extract it to C:\Users\Your Username\AppData\Roaming\Clickteam\Fusion Developer 2.5\Skins
It's not perfect since the thing is not meant to be using these legacy icons, but it's much more similar to 293 and older...
After extracting it, enable Skin editor toolbar on View menu, then select the new skin from it.