Looks like just a standard countersunk hex socket screw – DIN7991
2.5mm hex means it’s an M4 according to this link
https://shop4fasteners.co.uk/fasteners/socket-screws/socket-countersunk/socket-head-countersunk-screws-bzp.html
(Click on technical data tab and one of the images is keyed so you can see what you are looking at)
For countersunk screws you need to order by total length, not just thread length like you would with a standard cap head screw.
Hard to tell, but is your screw 8mm long?
If so, you need an M4x8 socket countersunk screw.
Here’s an ebay seller with what you need.
https://www.ebay.co.uk/itm/252472701245?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=lzbdE57DSHe&sssrc=2047675&ssuid=&var=551346517181&widget_ver=artemis&media=COPY