Many Galaxy devices have already received the April 2021 security patch, including the LTE variant of the Galaxy S20 Fan Edition. The LTE variant received the April 1 security update at the end of March, and two weeks later, Samsung has finally started rolling out the security update for the 5G variant of the Galaxy S20 Fan Edition.
The April 2021 firmware update for the LTE variant brought vulnerability fixes and performance improvements but didn't include any user-facing changes. The firmware update for the 5G variant could carry some additional changes alongside the April 2021 security patch.
The Middle East region was the first to receive the security patch for the Galaxy S20 FE 5G. Then the rollout expanded to the Far East. The security patch has firmware version G781BXXU2CUD1. You can check for the update in the Settings menu. Go to the "Software Update" section and tap on "Download and Install".
Meanwhile, renders of the Galaxy S21 Fan Edition, which is expected to be released in the coming months, have become available online.