Hope this may be of some help as I have has similar issues.
I run the gateway service as the default NT SERVICE\PBIEgwService, so looked in the log files under C:\Windows\ServiceProfiles\PBIEgwService\AppData\Local\Microsoft\On-premises data gateway on my on premise gateway server. In the latest GatewayErrors20230305.000000000.log I found the following error,
GatewayPipelineErrorCode=DM_GWPipeline_UnknownError
GatewayVersion=
InnerType=UnauthorizedAccessException
InnerMessage=<ccon>Access to the path 'C:\Windows\ServiceProfiles\PBIEgwService\AppData\Local\Microsoft\On-premises data gateway' is denied.</ccon>
InnerToString=<ccon>System.UnauthorizedAccessException: Access to the path 'C:\Windows\ServiceProfiles\PBIEgwService\AppData\Local\Microsoft\On-premises data gateway' is denied.
at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
at System.IO.FileSystemEnumerableIterator`1.CommonInit()
at System.IO.FileSystemEnumerableIterator`1..ctor(String path, String originalUserPath, String searchPattern, SearchOption searchOption, SearchResultHandler`1 resultHandler, Boolean checkHost)
As a test I have given ‘Everyone’ read permissions to that folder and straight away the failing data source connections can be brought online and I can use the original accounts to connect.
At the moment I can't say for certain that it ia as a result of me running the February 2023 update that caused the failure or maybe a change on our servers, but it does seem a bit of a coincidence.
