Jenkins jobs flood

I'm not sure where to file this, but this repository seems the closest.

I've noticed that tasks created by deb-build-jobs will trigger SCM rebuilds every minute for long periods of time. One of them that I disabled: https://arm01.puri.sm/job/debs/job/deb-plasma-phone-settings-buster+plamo-aarch64/

Because stages don't get cleared from nodes when they are finished, but it rather seems that stages are cleared after the whole job ends (?), in a flood of jobs all slots will instantly get filled and no slots will be available to proress to the next stage, causing a complete Jenkins deadlock waiting on master slots (see current situation and console logs).

It's not clear to me how to proceed from here.