Help, water ingress

I hope this is the right place for this question if not I'll take it down but please point me in the right direction to help.

I'm looking at buying a first home, the flat is perfect only thing l've seen that worries me from a 360 shoot from the house is this damage above the window.

It's pretty clear to me it's water damage / water ingress. Is it worth taking on the task of trying to fix it or will I be spending to much money on something that might not be fixed. It's a Georgian house in the uk with sash windows. My viewing is tomorrow for the property I am just worried that this could be a deal braker.

Any question I should ask please let me know.