There seems to be a lot of misinformation flying around. Here's [0] Google's support doc that clears up some of it.
The most important part is at the end:
"In some cases, senders may be able to know whether an individual has opened a message with unique image links. As always, Gmail scans every message for suspicious content and if Gmail considers a sender or message potentially suspicious, images won’t be displayed and you’ll be asked whether you want to see the images."
So Google apparently does not see read receipts as a problem. The privacy and security protections are about preventing other information (like ip, browser headers, cookies) from leaking, rather than read notifications.
If you care about maintaining your privacy, I would recommend disabling the new functionality.
The most important part is at the end:
"In some cases, senders may be able to know whether an individual has opened a message with unique image links. As always, Gmail scans every message for suspicious content and if Gmail considers a sender or message potentially suspicious, images won’t be displayed and you’ll be asked whether you want to see the images."
So Google apparently does not see read receipts as a problem. The privacy and security protections are about preventing other information (like ip, browser headers, cookies) from leaking, rather than read notifications.
If you care about maintaining your privacy, I would recommend disabling the new functionality.
[0] https://support.google.com/mail/answer/145919?hl=en&ctx=mail