移动端@font-face字体失效与字间距异常问题求助

我用纯HTML和CSS开发的个人作品集网站已上线，采用从网上下载的GT Walsheim Pro字体，桌面端显示完全正常，但移动端（包括iPhone）出现字体显示异常，比如首页横幅标题字间距莫名增大。目前仅在首页测试@font-face规则，问题解决前暂未在其他页面加载该字体。

我已排查过@font-face的语法、文件路径，确认标题元素使用的字体族名与@font-face定义完全一致，同时引入了ttf、woff、woff2、otf、eot、svg等多种字体格式。试过将URL路径改为单引号，无效；改用双引号后问题依旧。浏览器的平板/移动端预览模式显示正常，但真实用户的移动端和iOS设备上问题持续存在，也麻烦平板用户帮忙验证字体显示是否与桌面端一致。

当前@font-face代码 #

@font-face {
    font-family: "GT-Walsheim-Pro-Light";
    src: url("fonts/GTWalsheimPro-Light.ttf") format("truetype"),
         url("fonts/GTWalsheimPro-Light.woff") format("woff"),
         url("fonts/GTWalsheimPro-Light.woff2") format("woff2"),
         url("fonts/GTWalsheimPro-Light.otf") format("opentype"),
         url("fonts/GTWalsheimPro-Light.eot") format("eot"),
         url("fonts/GTWalsheimPro-Light.svg") format("svg");
    font-weight: normal;
    font-style: normal;
}
@font-face {
    font-family: "GT-Walsheim-Pro-Regular";
    src: url("fonts/GTWalsheimPro-Regular.ttf") format("truetype"),
         url("fonts/GTWalsheimPro-Regular.woff") format("woff"),
         url("fonts/GTWalsheimPro-Regular.woff2") format("woff2"),
         url("fonts/GTWalsheimPro-Regular.otf") format("opentype"),
         url("fonts/GTWalsheimPro-Regular.eot") format("eot"),
         url("fonts/GTWalsheimPro-Regular.svg") format("svg");
    font-weight: normal;
    font-style: normal;
}
@font-face {
    font-family: "GT-Walsheim-Pro-Medium";
    src: url("fonts/GTWalsheimPro-Medium.ttf") format("truetype"),
         url("fonts/GTWalsheimPro-Medium.woff") format("woff"),
         url("fonts/GTWalsheimPro-Medium.woff2") format("woff2"),
         url("fonts/GTWalsheimPro-Medium.otf") format("opentype"),
         url("fonts/GTWalsheimPro-Medium.eot") format("eot"),
         url("fonts/GTWalsheimPro-Medium.svg") format("svg");
    font-weight: normal;
    font-style: normal;
}

相关CSS代码 #

其中.homepage-banner-text-mobile h1是首页横幅主标题，我特意使用"GT-Walsheim-Pro-Light"并设置font-weight:bold，想实现介于Regular和Medium之间的字重，桌面端显示正常，但移动端完全失效。已有5位朋友测试，不仅h1字重未达到预期，还出现了未设置的异常字间距。.homepage-banner-text-mobile h4为横幅副标题：

.tablet-and-mobile-nav ul li a {
    color: #ffffff;
    font-family: "GT-Walsheim-Pro-Regular";
    font-weight: 400;
    font-size: 20px;
    padding: 28px 0px 13px 0px;
    display: flex;
    position: relative;
    text-align: center;
    flex-direction: column;
    text-decoration: none;
}
.homepage-banner-text-mobile h1 {
    padding: 17.14285714285714px 0px 5.142857142857141px 0px;
    color: #ffffff;
    font-family: "GT-Walsheim-Pro-Light";
    font-size: 30px;
    font-weight: bold;
}
.homepage-banner-text-mobile h4 {
    padding: 5.142857142857141px 0px 8.571428571428569px 0px;
    color: #ffffff;
    font-family: "GT-Walsheim-Pro-Regular";
    font-size: 20.57142857142857px;
}
.view-projects-button-mobile {
    border-radius: 20px;
    border: none;
    padding: 8px 49.5px 8px 49.5px;
    margin: 4.285714285714284px 5px 4.285714285714284px 5px;
    font-family: "GT-Walsheim-Pro-Medium";
    font-size: 18.21428571428571px;
    font-weight: 560;
    color: #0d0d0d;
    background-color: #ffffff;
}
.learn-about-me-button-mobile {
    border-radius: 20px;
    border: none;
    padding: 8px 45px 8px 45px;
    margin: 4.285714285714284px 5px 4.285714285714284px 5px;
    font-family: "GT-Walsheim-Pro-Medium";
    font-size: 18.21428571428571px;
    font-weight: 560;
    color: #0d0d0d;
    background-color: #ffffff;
}

.headline h2 {
    display: flex;
    justify-content: center;
    align-items: center
    flex-direction: column;
    text-align: center;
    font-family: "GT-Walsheim-Pro-Regular";
    font-size: 22px;
    font-weight: 400;
    color: #ffffff;
    margin: 81px 40px 0px 40px;
}
.body-text {
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    text-align: center;
    font-family: "GT-Walsheim-Pro-Regular";
    font-size: 15px;
    font-weight: 300;
    color: #ffffff;
    margin: 250px 40px 250px 40px;
}

内容的提问来源于stack exchange，提问作者David Xue