The latest version of ArcGIS 10.8.1 supports the latest PostGIS 3.0 very well. I installed the PostgreSQL 13.0 as well as PostGIS 3.0 spatial extension on my Windows Server 2019. This new version works very well with ArcGIS 10.8.1. I can now export and import my spatial dataset to the PostgreSQL server without problem.
I had some issues to work with the previous version of PostGIS on my ArcGIS. But recently, those issues were gone and I can freely use my PostGIS with ArcGIS flawlessly.
But unfortunately, I cannot edit the PostGIS spatial table directly from ArcMap. If we need to edit the PostGIS table or SQL Server table from ArcMap, we need a special license for that. But for now, I am pretty satisfied with it.
If you are new and want to set up your own PostGIS server, you can read the following guide.
To download the latest version of PostgreSQL and PostGIS, please visit the official website below.