I have just upgraded to 7 and it's literally slaughtered my VST & AU plugins with Failed Validations. Ones which were fine in 6. Its failed loads of big guns like my whole brand new Izotope Bundle of ALL their plugs, Kontakt 5 & 6, FM8, Massive, Absytnh, all the Soundtoys 5 bundle plugins, Every single Eventide plugin and half my Arturia collection..as well as the Air plugins also mentioned previously. I've just updated all these as well so they are latest versions. The list is way bigger but those were the main ones.
I use 7 as a slave on a second Mac Pro running a lower OSX intentionally so I have access to pre Catalina stability...Without the above plugins working..especially Kontakt then for me 7 is useless? Any advice please Paul?