Update 4/9/21: American Express has officially confirmed this, not sure it was needed considering the terms were updated on their own site (now removed) but good to know for sure.
Original post: American Express has updated the terms for Centurion lounges and beginning February 1, 2023 you’ll no longer get to guests access for free (terms have now been updated again and don’t show these terms, but you can view a screenshot below). Instead a fee of $50 will be charged per guest. If cardholders spend $75,000 within the prior calendar year (or current calendar year) the $50 fee will be waived.
This is an interesting change as for some people it’ll actually be a positive as it should help to reduce overcrowding. For others this will be a huge negative as Centurion Lounge access with guest access is the main perk of the card. This seems to favor business travelers rather than leisure travelers. This was also one of the rumors surrounding the annual fee increase on the personal Platinum card.