You are spot on with your observation skills.
Support for Zorin OS 12.4 ended April 29, 2021.
I am still using Zorin Lite 12.4 on one of my machines - it sees Shop Use so the security updates are of less concern.
If you are running 32 bit, Zorin OS 15.3 Lite is available in 32 bit. Sadly, Zorin OS 16 will not be offered in 32bit.