Same for me I am running 11.7.10 the most efficient OS for my 2012 Imac and it will update to 13, however the 13.OS has problems with my hardware, this being an Apple incentive for you to purchase a new model. This being the case I downgraded to Big Sur being the last supported model of the OS to run on my hardware. This is also why I keep My QNAP NAS running as the key preference for my data both locally and remotely while also being able to securely encrypt the data
Same for me I am running 11.7.10 the most efficient OS for my 2012 Imac and it will update to 13, however the 13.OS has problems with my hardware, this being an Apple incentive for you to purchase a new model. This being the case I downgraded to Big Sur being the last supported model of the OS to run on my hardware. This is also why I keep My QNAP NAS running as the key preference for my data both locally and remotely while also being able to securely encrypt the data