The touch-related bug that was known to be impacting the Apple Watch Series 9 and the Apple Watch Ultra 2 also affects the Apple Watch Series 7, Series 8, and Ultra 1, Apple said in a memo shared with Apple Authorized Service Providers.
Service providers have been told not to replace watches for the ghost touch problem, instead instructing customers to fix the issue through a force restart. A force restart can be initiated by simultaneously holding down the side button and the Digital Crown for 10 seconds. AASPs have also been asked to make sure affected Apple Watches are running the latest version of watchOS.
Apple first began looking into the touch-related problem affecting some Apple Watch models in February. At the time, it was a bug that had been seen on the Series 9 and the Ultra 2. Apple Watch owners were experiencing "false" or "ghost" touches on the display, which could cause the screen to "jump erratically" or exhibit unexpected behavior without user interaction.
A fix for the ghost touch issue was added in watchOS 10.4, so presumably that version of the software addresses the issue on all impacted models. If not, the wording of Apple's memo suggests a further fix will be coming in the near future.
Source: Macrumors