If you go to the website:
https://koina.proteomicsdb.org
it redirects to a page which says "Under maintenance".

A user named "ProteomicsDb" posted the following on X 10 hours ago:

Due to a failure in the cooling system of our server room, ProteomicsDB is currently unreachable. We expect the servers to be down until Monday, 5 August at 12 p.m. We apologize for the inconvenience!

-- Nick