iCal link returning a 404

[heyimjake]

As of 2-3 weeks ago, any generated iCal link is returning a 404 with the message:
Invalid Firefly account. Please authenticate!

I have tried multiple school accounts, and multiple re-authentications.

[JoshHeng]

Hello! Unfortunately I don't have a Firefly account anymore so am unable to investigate/fix this.

If you fancy looking into the code, the error is thrown here or here. I'm getting this corresponds to this or this.

At a guess, Firefly may have changed how their API works internally