Google’s latest security update has caused data connectivity issues for some Pixel users, particularly those on the Pixel 6 series and newer models. The problem affects mobile data, causing devices to lose connection or display an exclamation mark in the status bar.
Affected users have reported overheating issues, but phones can still make and take calls. Two possible fixes are resetting the mobile network settings or disabling Wi-Fi calling by going through Settings > System > Reset options > Reset Wi-Fi, mobile & Bluetooth or disabling 4G/VoLTE calling feature.
While some users have experienced issues with data connectivity, it’s not a widespread problem. Google has not yet addressed this issue in an official update, and users should try these fixes before reporting the issue to others.
Source: https://www.phonearena.com/news/pixel-users-report-drops-in-data-connectivity-after-loading-the-december-security-update_id166137