Is my iMac to old for the Current OS?

Hi GoodyearTechSupport,

It simply means that the iMac (in terms of official support) can only run macOS Catalina as its last OS.

If you have any apps that are no longer compatible with macOS Catalina and require a newer version of macOS, then yes - that could cause issues depending on your workflow.

It may be technically possible to upgrade your iMac beyond macOS Catalina using third-party tools and scripts (such as OpenCore Legacy Patcher), but please note that Apple doesn't provide any support or warranty for them, and we typically don't recommend using them here. Also, they often have to downgrade system security to add modifications to support your Mac.

What year model is your iMac?

see > Identify your iMac model - Apple Support

Note: the "Newest compatible operating system:" is listed in the info section for each model.

What do you mean is it going to be an issue?

If it can’t upgrade past Catalina, it can’t upgrade past Catalina.

I don’t understand your question.