Today, I received an email from Dropbox with the subject "Your credit card expires soon! Don’t forget to update your info" with the following text:
Your credit card is about to expire! Update your billing information to make sure your Dropbox Plus features aren’t interrupted. Click the link below or log in to your account on dropbox.com, go to Settings, select Billing, and update your payment method.
Update your billing info now
If you don’t update your billing info by 2022-10-18, your account will be downgraded to a Basic plan with much less storage space.
Thanks,
- The Dropbox Team

When I go to update my credit card, I can see that the expiry is in 2027 (see screen shot below).

I tried contacting Dropbox Support through https://www.dropbox.com/support/email , but it is impossible to contact them with a billing issue without adding information about a billing transaction, and it is impossible to attach images.