" Dear PantherMedia Contributors we have transferred your account information and balances and are currently migrating your images. We will notify you once the migration is complete. In the meantime, you can start uploading new images. Check documentation for uploading instructions."

This was a while ago. I think it is taking a long time by now. Also, there is a payout on hold, but first an ID and a fw8ben have to be uploaded. Anyone else here with a Panthermedia account as well?

Yes, I also have a Panthermedia account and previously had a Yayimages account.
The outstanding money with Panther was correctly transferred to Yay and has already been paid out by Yay (I already had the tax form and ID there).
So far, Panther has kept all its promises to me.

The pictures have not yet arrived on my Yay account, but that could take up to 3 months.

Ah ok, thanks. So everything will be fine.

However, I'm not sure what will happen on the Yayimages side afterwards. I had an account there that generated between 10 and 50 sales every month until September 2023 (always for exactly $0.25 per sale), but since September I haven't had a single reported sale there.

Exactly my experience. Very suspicious. That is the reason a deleted all my images after 5 months of no sales. Yayimages cannot be trusted.

My prediction with this transfer from Panthermedia is that it will take a long time to transfer the images and may never arrive. Secondly, even if your images arrive at Yayimages I predict you will not see another sale again.  I my case my 56 euro at Panthermedia was transferred to Yay where it now shows 56 US dollar (ignoring the difference in the exchange rate between euro and US dollar) and I cannot request a payment because the minimum for payment is $60.  Pantermedia was a reasonable earner for me and this change is really a very disappointing move from them.