There is a list of the bugs that have been addressed only with each release of ESRI software.  There is no publicly available list of those that are still open or recently identified.  You can try searching on the support website https://support.esri.com/en/ if the bug has some age to it.

The current ESRI bugs that are affecting access to or functionality of our web services at this document version are the following:

BUG-000128770

The Export Tiles Map Server Cache tool fails to execute when caches are stored in the Amazon Simple Storage Service (Amazon  S3) cloud store. This should be resolved upon their prospective upgrade to ArcGIS Enterprise 10.8.1. See https://support.esri.com/en/bugs/nimbus/QlVHLTAwMDEyODc3MA==

BUG-000137514

Image services prevent offline map areas from being downloaded in ArcGIS Collector and ArcGIS Field Maps – limitation is undocumented. Only in a custom app this can be resolved with the newest version Javascript API. This will not be resolved yet at ArcGIS Enterprise 10.9.x, and ESRI AU has submitted it to ESRI Inc. as  defect for development consideration. See https://support.esri.com/en/bugs/nimbus/QlVHLTAwMDEzNzUxNA==

ENH-000136006 [Enhancement] - in ArcGIS Pro 2.8 external Spatial Portal users

This bug relates to ArcGIS Pro 2.7.x Users that are logging into Spatial Portal via QGov account (identity.qld.gov.au) using their Queensland Government accounts cannot authenticate.

Give ArcGIS Pro the ability to log into ArcGIS Enterprise when Portal is configured with "One identity provider" and this provider redirects the user to a cascading federation of SAML IdPs.  Still not fixed in 2.7.3.

This issue has been resolved with an enhancement in ArcGIS Pro 2.8., and the workaround is as follows:

1- Connect or Switch to Spatial Portal and click on Sign in:

2- Please make sure you click on Sign In Using Browser:

3- In the newly opened browser, sign in with your QGov username and password:

4- In the OAuth2 Approval webpage copy the code and paste it into ArcGIS Pro:

5- In ArcGIS Pro Submit the code in the ArcGIS Sign In window: