How we can prevent a List which has its Create,Edit,Display forms customized using PowerApp from been rendered using classic UI forms

Question

I have the following:-

1. custom list inside a classic team sub site
2. the custom list has its create,edit & display form customized using power app.
3. the custom list has the following setting to also render it using New Experience:-

so i thought that the list will always render using power app forms, but what is actually happening is that the users will get the option to render the list using classic UI, as follow:-

So now all the business rules which i have applied inside the power apps forms will have to be applied to the classic UI as well which is not logical.. so my question is how i can prevent a List which has its Create,Edit,Display forms customized using PowerApp from rendering using classic UI forms?

second question. i have a modern communication site and i have the same list and settings, and the users will not have the option to render the list using classic UI,, so is my problem because i am using classic Team Sub-site?

Can anyone advice/help with my above 2 questions please?

Answer 1

There is no OOB way to remove "Return to classic SharePoint" link.

You may try to use third party tool as described below or vote this User Voice:

https://support.shortpoint.com/support/solutions/articles/1000291926-hide-return-to-classic-sharepoint-link-in-team-sites#:~:text=If%20you%20do%20not%20want,Theme%20Builder%20to%20hide%20it.

In addition, there is no left navigation in communication site,which is different with team site.