We've seen 3800 Swedish card donation attempts result in Status 50 3DSecure errors today (from the GC console, not Zendesk!). Overall 5800 card donations in SEK have reached Civi, so the rate of status 50 errors seems high.
Donors are reporting a new error in the iFrame, where they receive the message You will be redirected, but then nothing happens.
One donor confirmed that they may be using a script-blocker of some sort, and we've asked for technical/browser specs from many more.
Is it possible to check whether there is an error in the 3DS process? Perhaps one affecting mobile more intensively?
Even if there is not a bug, could we ask Ingenico to improve the message in the iFrame? Something like You will be redirected. If you are not, please turn off browser add-ons, or email firstname.lastname@example.org for more information.