Vue.js page inside iframe not showing on Firefox

We have a Vue.js page contains a Echarts pie draft, and we want to show it in another project, which is using jQuery.
It shows perfectly both on Chrome and IE, but on Firefox there's nothing showing.
We tried to replace the Echarts page with some basic numbers in the template, but it's still empty in Firefox.

This is what it looks like in chrome:


And this is Firefox, which only has an empty app tag:

Any help would be appreciated.


edit:
I'm using Firefox93 on 64bit, there are no errors showing in the console.
This is how we inserted the iframe:

from Vue.js page inside iframe not showing on Firefox