I can not get the Chome pop-up again after dismissing it. Is it possible that Chrome now has some sort of mechanism that prevents recurring users from receiving the subscription option after a while if they ignore it?
Yes, that's correct. Chrome indeed has a mechanism that automatically blocks the pop-up if the user continues to close it.
It is called a permission embargo, which is a feature of Chrome. If the user dismisses your permission request 3 times we will stop showing it for 7 days. This is to stop spamming users with permission requests.
It's controlled by Chrome itself.