The EWWW Image Optimizer has detected excessive re-optimization of multiple imag

From your debug information, it looks like benign (normal) behavior, so you can just hit reset, and not worry about it. It’s just a result of using the scheduled optimizer to optimize the plugin folders, thus the “excessive re-optimization’ alarm is tripped once you’ve done enough plugin updates.

How would I determine whether I have a real problem that needs to be fixed vs a reset in the future?

Alerts that are sometimes important and sometimes not always make me a little nervous.

If it is a real problem, it will come back within a couple days (or less, depending on how much traffic your site sees). The key thing that I looked at was which images it listed.

Almost all of them were images from the wp-content/plugins/, which is normal considering those images will be refreshed every time a plugin is upgraded.

If in doubt, feel free to post your debug info next time it pops up (which it will so long as you have EWWW scheduled to optimize the plugins folder).