I heard from Matt Glantz that, due to multiple complaints regarding accidental markings on cards occurring at the WSOP this year, they might bring back the well-liked playing cards from 2005 for certain events.

2005???

Yes. 2005 was the first year for the WSOP at the Rio, and apparently they ordered a shitload of decks that year -- far more than they needed. I assume that they ordered these decks to be used over the next several years. However, starting from 2007, they ordered new decks (remember those awful Poker Peek decks with Jeffrey Pollack's signature on them?), and the '05 decks sat in a warehouse, forgotten about for 10 more years.

Fast forward to 2017. Someone realized that those 2005 cards were still in storage at the Rio, so they were retrieved. I saw different cards at the $10,000 Limit Holdem event -- ones I remembered being very similar (or identical) to the ones we used in 2005.

A few days before playing the $10k, I asked Seth Palansky (in person) if the cards would be changed, and he said they would not.

I didn't bother to ask about the 2005 card rumor, but it appears that indeed the cards were changed for the $10k events -- at least if my memory of the 2005 cards is correct. They were definitely different cards, though they were by the same manufacturer as the current ones (Copag).

It's also important to note that Seth Palansky mostly works with media, and does have his hands in the operation of WSOP events. It's possible they made this change and never informed him.

The 2017 Copag cards are still being used in all lower and medium buyin events, as well as at all satellite and cash games.