Defender Danique Kerkdijk is leaving the club when her contract expires at the end of June to join Dutch club FC Twente.
Kerkdijk joined Albion in 2019 from Bristol City and went on to make 56 WSL appearances to help establish the club in the Women’s Super League.
The 26-year-old is returning to Twente for a second spell, having played there between 2013-17.
Head coach Hope Powell said, “We’re really sorry to be losing Danique but totally understand that she wants a fresh challenge at a club she knows well.
“It has been hard for all our overseas players during the pandemic not being able to spend more time with their families. Danique has always been a brilliant professional on and off the field and everyone around the club will miss her.
“We wish her all the best for the next stage of her career. She knows she will always be welcome back at Brighton.”
The German midfielder is out of contract this summer but talks of a new contract for the 30-year-old has been mysteriously quiet.
Graham Potter has previously said he wants his key man to stay but any discussion look set to be held at the end of the current campaign.
"I think we do that after the season,” Gross said to BBC Sussex. “We will see what's going on.
"All I can say is I've been here for five years, that's a long time when you come from abroad but I'm enjoying it here.
"From the start until now we [him and the fans] have had a great journey and I still enjoy it."
Gross joined Brighton for just £3m from German club FC Ingolstadt 04 in 2017.
Lars Dendoncker has been released by Brighton. The central defender – who is the younger brother of Wolves midfielder Leander - joined Brighton from Club Brugge in August 2020.
The 21-year-old Belgian made seven appearances on loan to Scottish Premiership club St Johnstone before his recall in January.