Here's a sample app with vuetify 1.x and 3.x conflicting. App 2 (vuetify 3.x) styles are wrong if you access app 2 after accessing app 1 (Vuetify 1.x). If App 2 (vuetify 3.x) is accessed directly or after refresh it looks good. Conclusion, is that vuetify 1.x is conflicting with vuetify 3.x.
Code https://github.com/eolamisan/vuetify1x-vuetify3x
App 1 (vuetify 1.x) http://localhost:11443/#/app1
App 2 (vuetify 3.x) http://localhost:11443/#/app2
In the file packages\root\src\bootstrap.js I played around with enabling / disabling stylesheets dynamically between apps. It seems to help but I wonder what the issue is and if there is something better that can be done.