I've opened a support case (#2318973), but will post here for consideration: 

#1 - DroptdownTags still running multiple OnChange Events

Version 2.3.5 release note states: 

Fixes

• We fixed the DropdownTags OnChange event to run only once, as expected.

Nevertheless, DropdownTags keeps running multiple OnChange events if you promote any changes on the list used in its SelectedItem property.

In that case, each change will result in additional and cumulative On Change events: 

1. If the app, via a screen action, removes a tag from the SelectedItem list, one more On Change event will trigger each and every time, for now on, until DropdownTags is destroyed. 
2. If app, via a screen action, later add a tag to the SelectedItem list, one more On Change event (two additional events now) will trigger each and every time, for now on, until DropdownTags is destroyed.

I humbly suggest that changes to the SelectedItem list don't trigger any OnChange event, letting the user handle those changes in the screen action that initially promoted those changes. 

#2 - Return of rendering problems

Version 2.3.1 release note states: 

Fixed Issues:

• DropdownSearch and DropdownTags now render even when used with an empty list.

Now, with Version 2.3.5, if the screen renders with the Visible property of DropdownTags enclosing container set to False and later this property is set to True (making the enclosing container visible), DropdownTags won't render. This behavior will result in the error "Cannot read property 'Destroy' of null" if the user navigates to another screen. 

Actual Platform Version: 11.7.3.5968 Internal Version

Actual Development Environment Version: 11.6.29.11480