Hi,
It’s expected that you don’t see straight edges for the glitch out waveform. There’s a bunch of parasitic capacitance and inductance from the FPGA leads, the traces, the MOSFET input, etc. that don’t have much of an effect at lower frequencies, but come into play when you’re at this time scale. It’s the same case for the Vcc rail. For example, changing the length of the cable between you and the target has a large effect on what the glitch wave looks like.
Alex