The Control Center swipe up has moved to a quick press and release of the flat oval side button (see picture)

Use Control Center on Apple Watch - Apple Support
DO NOT hold the button, as that brings up Emergency Services
You will find the iPhone ping in the Control Center display after you press and release the flat oval side button. If it is not there, then scroll to the end and tap "Edit"where you can add missing services, and rearrange them in an order that is to your liking.
Settings -> Accessibility -> Side Button Click Speed
“Side Button Click Speed” can adjust the press and release timing, so you get the Control Center display every time. Adjusting The "Side Button Click Speed" is also useful for Apple Pay’s double press and release. There is “Default” (sub second timing of needed), “Slow” (up to a second between press and release), and “Slowest” (up to 2 seconds between press and release). I like the “Slow” setting.
NOTE: Slow and Slowest settings do not mean you have to wait a full second or 2 seconds between press and release. It just means you do not need to be super fast.