it's not just the parts that covid has affected. it's the lockdowns. as yoshi said...they can't get their server engineers out to the datacenters to set up new servers. I imagine same reason they don't use third party hosting like amazon or google servers. they like to be self sufficient and probably want to protect whatever trade secrets they have.
also it allows them to conduct their maintenance on their own schedule. other games that rely on third parties or whatever have to do regional launches of patches and staggered downtime based on the region's clock