The second monitor's panel must be separate, whether or not the main monitor uses an application frame. Please refer to this thread to separate the rows of panels.
https://community.adobe.com/t5/photoshop-ecosystem-bugs/macos-14-1-photoshop-2024-v25-0-0-toolbar-bug/idc-p/14195780#M94643
This is an Apple or Adobe bug, but until it is fixed, please use this method for now.
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