Occasionally, apps will bundle code from outside sources along with their app. Stack trace frames including outside code will never be mapped using source maps as they are outside the build process from the user's app. An example of this could be a pre-built chat module that a user imports to their app. Users do not care about these frames generally and understand that they are from outside of their app.
In these cases, you can use Stack Trace Rules to "cut" out these frames so Sentry will not consider them as a part of the app this will also prevent Sentry from using them for grouping purposes.