Earlier this month, Microsoft posted on the docs site a few changes and deprecation notices related to Power Apps Portals. This notices are not yet being removed from Power Apps Portals, but announced that they will be removed in a future date.
The list of deprecations include the following features:
- OAuth 2.0 implicit grant flow within your portal
- List OData feed
- Portal content editor
- Portal search using Lucene.NET search
- Content Delivery Network for US Government
- Table permissions changes for forms and lists on new portals
- SameSite mode changes
- Tracking for webpage, web file, and login (retired in version 9.3.4.x)
If any of the features above are being used in your portals, you should go ahead and start preparing for their retirement and update your portal code to find some alternatives. The Microsoft Docs announcement is available by clicking on the link below
https://docs.microsoft.com/en-us/power-apps/maker/portals/important-changes-deprecations