Software Update Required to Connect to iPhone. Is this an update to Catalina or Big Sur?

Lawrence of Berkley wrote:

Good day. I am running Catalina 10.15.7 on a Mac mini and have an iPhone 11 running 14.2. When I connect, I am getting the prompt to run a software update. Is this update trying to get me to install Big Sur, or is this an update to Catalina?

My Mac Mini is also my Final Cut Pro edit system. I am not going to install Big Sur yet, until we've had a couple of OS 11 updates and I'm sure FCP is running with no issues. I just want to make sure I'm not installing Big Sur.

If you see "Software update is required to connect to your iOS device" on your iPhone

https://support.apple.com/en-us/HT208831

It is an update for Catalina for compatibility (?) with iOS 14.2.