Many open source programs use GitHub for management of the projects and releases, but GitHub is running a monitoring systems on connections from a single source and then blocks new connections when a trigger limit is reached.
HACS and especially HA hits this limit often.
When that occur then the HA and HACS need to wait for the counter in the monitoring system to go down again before it can resume.
It will happen automatically so you just have to wait.
HA and HACS have several locations it gets code pieces from and since HACS is a portal to all the different projects u der it then it needs to keep an eye on those for updates.
The amount of code means it will have to do this in steps, so it reads as many projects as possible until it hits the limit and then wait till it can read again where it will then continue with the next batch of projects. Eventually it will be finished.
Remember that it is vacation time and some people relax with working on their pet projects, like an integration for HA, so there are probably many extra reads at the moment, since change logs and descriptions of many projects are changed.