Forum Discussion
Web Property Bag and NoScript Sites
http://www.techmikael.com/2017/02/gaps-and-differences-between-group-365.html "You cannot programmatically update the site property bag on a modern site, but in many cases you can work around thi...
You can turn off NoScript, update the propertybag, and turn it back on! Here is now PnP does it: https://github.com/SharePoint/PnP-Sites-Core/blob/master/Core/OfficeDevPnP.Core/Extensions/TenantExtensions.cs
(Search for DenyAddAndCustomizePages)