Chunching has dropped to 1/3 or less

I think the file Christian is referring to is the one called 'job_log_einstein.phys.uwm.edu.txt'. If the OS upgrade was performed in-place over the existing installation, it should still be present in the location stated, and should contain entries from both before and after the change in OS - they will provide the useful comparison. If the hard drive was reformatted without an external backup first, of course, that won't be possible.

A sample entry from my log reads

1467194835 ue 34886.100421 ct 647.388500 fe 590000000000000 nm PM0144_01111_314_0 et 30921.194592 es 0 I would break that down as

[pre]1467194835 // unix timestamp of task completion
ue 34886.100421 // original runtime estimate
ct 647.388500 // CPU time used
fe 590000000000000 // FLOPs estimate (task size)
nm PM0144_01111_314_0 // task name
et 30921.194592 // elapsed time (task run time)
es 0[/pre]

You have the right file. You need to check from when the first (oldest) entry is from. For this you need to convert the first column from unixtime to normal time using something like http://www.unixtimestamp.com/. If this is before the FC 19->22 migration than you need to see if the runtime in the third column (the number after ct) is increasing at some point and you can then convert the timestamp to normaltime and see if this is around the date where you migrated. You can do this for the other projects on those computers too.
If the oldest entry in the file is the time you migrated than you can't compare runtime before and after and habve to look for other reasons. Maybe one of your projects ran out of work and another project that is not giving you this much Credits took it's place.

Btw: Here is the breackdown of projects for you: http://boincstats.com/en/stats/-1/user/detail/549393/projectList By clicking on the little image on the right hand side of each project line you can see details for this project. On this page there is a button "Charts" where you can see the chart for each individual project. For Einstein@home I see the same drop as can be seen in your BOINC combined image and it seems to be the most significant one but WCG and Asteroids Numbers are also lower after the migration.

What Einstein@home Apps did you run before the Update? If you used to run GPU apps before and now you are not (because the GPU is not recognized by BOINC e.g.) that would explain the drop in Credit. You should check your BOINC Manager log messages on all three machines.