A recent change in Google Chrome version 85 has changed the way scrolling coordinates are calculated and can cause a user to experience trouble scrolling up to previous messages.
Note: This issue does not impact the Symphony Desktop Application (SDA) version of Symphony
There is a fix in progress to address this issue but it is not deployed yet. If a user is not in a position to use the SDA version of Symphony, there is a current workaround for this bug found by navigating to chrome://flags in the address bar and disabling the CSSOM View Scroll Coordinates flag (Figure 1):

Figure 1 CSSOM View Scroll Coordinates
After disabling this setting, the user will need to close all browser sessions and relaunch them. The scrolling issue will then be resolved.
Note: Do not use Incognito mode for this change