I think you have it slightly backward there. What
@Maeiourk did was add extra spacers to push the GPU out more for the 3080 FE - it creates more room between the back of the card and the plastic insert as well as the PSU.
What
@dondan recommended was, if you want to create more room between the GPU and the side panel, is remove the currently installed 5mm spacers that the PCIe riser is screwed into and use washers and an 8mm long M3 screw to screw the PCIe riser into the case (held stable with those washers, instead of the spacers) to get you a few mm
That *should* help you fit cards like the EVGA 3080 XC3 since they only protrude the double slot size by a few mm