Why does my custom DOMPDF font work locally but not in Docker production?

I'm using DOMPDF 3.1.0 with a template HTML in public/templates/reports and custom fonts located in public/templates/reports/fonts.

I defined the font in my CSS as follows:

CSSCopied
@font-face {
        font-family: "Ubuntu";
        src: url("./fonts/Ubuntu-Regular.ttf"); // I tried absolute path as well, no effect
}

body {
        font-family: "Ubuntu", serif;
        font-weight: 400;
        font-style: normal;
        font-size: 10pt;
}

And configured DOMPDF with these options:

PHPCopied
$options = new Options();
$options->setIsRemoteEnabled(true);
$options->setFontDir(APPPATH . '../public/templates/reports/fonts');
$options->setFontCache(APPPATH . '../public/templates/reports/fonts');
$options->setChroot(APPPATH . '../public/templates/reports/');
$this->dompdf = new Dompdf($options);

Everything works as expected on my local Apache server, but in my Docker container using the image below, the font falls back to the default even if I set a defaultFont on $options.

Docker image details:

DOCKERFILECopied
FROM php:8.3-fpm-alpine3.20

...

WORKDIR /var/www/html

COPY . .

RUN apk add --no-cache curl \
    && curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer \
    && composer install --no-dev \
    && chown -R www-data:www-data . \
    && chmod -R +r public

What could be causing the custom font to work in development but not in my Docker production environment? Any insights or solutions would be appreciated.