Transition day hell with my 4-year-old

Fridays are rough. My 4yo cries when I pick her up from her mom's every single time, like I'm kidnapping her. Then Sunday evening when I have to take her back she's clingy and sad. I know transitions are hard for little kids but it breaks my heart every time. Her mom says she's fine 5 minutes after I leave. How long does this phase last? Anyone else dealing with this?