Generated .u3m8 file cannot be played by videoJS in Firefox

[town-paddy]

PC: Ubuntu24.04LTS

In nginx.conf, configured like bellow:
rtmp {
server {
listen 1935;
application app {
live on;
hls on;
hls_path /var/www/hls;
hls_fragment 7;
hls_playlist_length: 3600;
}
}
}

and run ffmpeg like this:
ffmpeg -f video4linux4linux2 -i /dev/video2 -c:v libx264 -preset uldrafast -an -f flv rtmp://localhost/app

I confirmed there are .ts files and .m3u8 file.create html file like this:

If accessing this html file with Chrome, .m3u8 was played. But with Firefox, video was infinitely loaded.