When I use the old Gmail I use this method:
https://mail.google.com/mail/u/0/#inbox/1630209116a3af45 and thread ID is:
In the new Gmail, the same thread link is:
https://mail.google.com/mail/u/0/?zx=3xcdey2cogvc#inbox/FMfcgxmZVPbZvwJWCvBMvjxglSMPvsvW and there is no option to find it.
I also looked in the HTML source of the page and the thread ID is not there.
All of my searches show only the old Gmail behavior (like this: https://support.cloudhq.net/how-to-get-thread-id-of-a-gmail-thread/).
I want to find out how I can locate the thread id.
(I also tried to find it in the "show original" option, but I can find only the message id, and it does not help.)