Users accounts gets locked when connecting to FAS Enabled Windows 2019 VDA. Its happens for Reconnect as well as new session.
Issue is seen mostly when Fast reconnect feature is enabled on VDA along with bad Password limit on AD is set to 3.
Create the following RegKey and the feature is turned off to disable Fast Re-connect
HKLM:\SOFTWARE\Citrix\Reconnect
FastReconnect
REG_DWORD
0x0