Having issues with users reconnecting a disconnected Citrix Virtual Apps and Desktops session? These keys might help you. Citrix support confirmed, that they help starting at Server 2016 VDA.

Fastreconnect is a feature that was introduced by Microsoft to enhance session reconnect through RDP, but through Citrix ICA it seems that is does not improve anything.

HKEY_LOCAL_MACHINE\SOFTWARE\Citrix\Reconnect
FastReconnect REG_DWORD 0

HKEY_LOCAL_MACHINE\SOFTWARE\Citrix\Ica\GroupPolicy
EnforceUserPolicyEvaluationSuccess REG_DWORD 0

References:

https://www.reddit.com/r/Citrix/comments/x6frfq/ltsr_2203_disconnected_sessions_are_lost_upon/