css transition for var inside “background: linear-gradient” not working in firefox but working in chrome

I wanted a smooth transition of “background: linear-gradient” color when scrolling(with transition and var).
It works fine in Chrome, but in Firefox the transition is instantaneous.

I have no idea what im doing wrong

My test code. On scroll(js script) change class for div from “item-static” to “item-sticky”.

Html

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="style/style_test.css">
    <script defer src="js/test.js"></script>
    <title>Document</title>
</head>

<body>
    <div class="target static-item"> Lorem ipsum dolor sit amet consectetur adipisicing elit. Sapiente alias quod ullam.</div>

    <div class="big-box" style="height: 120vh; background: black;"></div>
</body>

</html>

Css

@property --myColor1 {
    syntax: '<color>';
    initial-value: rgba(85, 85, 249, 1);
    inherits: false;
}

@property --myColor2 {
    syntax: '<color>';
    initial-value: rgb(255, 255, 255);
    inherits: false;
}

.target{
    top:0;
}

.flex-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    top: 0;
    z-index: 3;
    background: white;
}

.sticky-item {
    position: sticky;
    --myColor1: rgb(255, 255, 255);
    --myColor2: rgb(255, 255, 255);
    transition: --myColor1 1s ease-in-out, --myColor2 1s ease-in-out;
    background: linear-gradient(180deg, var(--myColor1) 0%, var(--myColor2) 100%);
}

.static-item {
    position: static;
    --myColor1: rgba(85, 85, 249, 1);
    --myColor2: rgb(255, 255, 255);
    transition: --myColor1 1s ease-in-out, --myColor2 1s ease-in-out;
    background: linear-gradient(180deg, var(--myColor1) 0%, var(--myColor2) 100%);
}