@mollyllll I am not seeing it either. However, my gut is telling me that its removal was intentional as, while some surely found it useful/handy, the action has caused a lot of grief over the years for a lot of people.
I will ask the support team and will report back here.
BTW, if you are using a paid Miro subscription, you can open a Miro support ticket by following these instructions:
https://help.miro.com/hc/en-us/articles/360020185799-How-to-contact-Miro-Support#h_01F010RXA0E1S9C0WFQYX75R6C
Context for all readers:
This is the feature being discussed:
https://help.miro.com/hc/en-us/articles/360018261813-Frames#01H7YR4H1DZ1WY2ZNAV8HZEGC8