I've added the linenumbers-plugin here, as it too has this issue now that workflow-job 2.26 is released. In my case, it seems to generate hundreds to thousands of copies of the original log file, all named with "deprecated" (e.g., deprecated5973622952721928030.log). I haven't figured out what causes the particular quantity of these files (I've seen over 6000 created by a single build), but it seems perhaps related to how the build was executed – triggering a build directly generates 1, but triggering a build from another build (in my case, a Pipeline build that spawns a number of builds to do a regression test) generates hundreds to thousands of copies. These all coincide with log messages in the Jenkins log like:
Given the impact to the master node to store this number of files (6000 files = 14GB for a single build, in my case), and unless I know it's something other than this bug that causes it, I'd think it makes sense to raise to Major (if not Blocker), if the affected plugins don't have their own issues tracking this problem.