There is something seriously wrong with GOG's servers today. I hope someone from GOG sees this so they can fix it. Trust me, this is not just a GOG issue. This is Steam will always be first when it comes to updates problem.
there's no denying it's been in something of a decline, whichSteamDBcharts can show quite well since 2016. It had a big blip in 2019 but clearly trending back down again.