PSA: WordPress 5.6 changes the filename of jQuery core. If you’re using Autoptimize and you have jQuery excluded (which is default) you will want to update your JS optimization exclusion list from
Update: Autoptimize 2.8 will automagically fix this, urgently looking for some testers to download https://github.com/futtta/autoptimize/archive/beta.zip (make sure 2.7.8 is disabled when enabling the beta). If all goes well and I get some confirmation the update (which has a lot more then just the fix) will go out today!
Update2: AO28 was released, all is (or should be) OK now :)