An initial file sourcing a second file, which in turn sources a third file, which in turn sources a fourth file, ...., which in turn sources a 100th file.
Anything but that.
ShellCheck found a chain of 100+ files sourcing each other. It assumed there must be some internal bug, so it stopped.
If this is intentional, you can cosmetically ignore this message.
ShellCheck is a static analysis tool for shell scripts. This page is part of its documentation.