File download using anchor download attribute doesn't work on iOS Chrome and iOS Firefox

[sylvie-uxe]

I have an anchor with a download attribute for saving a calendar file .ics of the GitHub planned contributions.
When the user clicks on the anchor, a *.ics file is generated from the graph:

const icsFile = new File(data, "my-github-graph.ics", {
        type: "text/calendar"
});

Then, an URL is created for this file:

if (icsFileURL) {
        window.URL.revokeObjectURL(icsFileURL);
}
icsFileURL = window.URL.createObjectURL(icsFile);

Finally, the href of the anchor is programmatically set to this URL:

const saveAsCalButton = document.getElementById("save-as-calendar");
saveAsCalButton.onclick = (event) => {
        event.target.href = generateCalendarFile();
};

It works fine on all desktop web browsers and on iOS Safari but not on iOS Chrome and iOS Firefox where a click on the anchor doesn't do anything. The href is correctly set to, for instance: blob:https://my-github-graph.web.app/b0037bb7-f20f-4e26-b9c0-5f4b32f486c1.

Stackoverflow issue