I really struggled removing my Velux blinds which were fitted in 2002. The front face overlapped the frame as has been mentioned elsewhere so twisting was impossible.
I thought about the flat bladed knife solution but decided to use a lightweight pin hammer, with a wedge shaped head, between the blind and the glass. I slid a piece of thin plywood between the hammer and glass to spread the load. It then levered out, relatively easily, but coming away suddenly so be careful!The brackets in the frame are different.
The left hand one has a hole in. The right hand one has a curved slot in, open at the bottom end. They are a push fit into 2 predrilled holes (each) in the frame. When fitting a genuine Replacement Velux blind one of the screw holes coincides with one of these holes so filled that using a bit of dowel, or wood filler would do. Hope the new blinds last another 18 years, but at least it's more obvious how they come off.