Photoshop 25 Generative Expand creates weird shapes

Please try to disable the option to "Use Graphics Procesor" from Photoshop by going to Preferences, then Performance. Once done, quit & relaunch Photoshop to check if that helps.

If it helps, you can check out the steps suggested here:   https://helpx.adobe.com/photoshop/kb/troubleshoot-gpu-graphics-card.html

Take a look especially point 7 in the "Troubleshoot GPU and Graphics driver" section.

Is your system up-to-date? Do you have installed all recent updates and patches for the operating system and the device drivers, especially the graphic driver. If you have a NVidia graphic card installed, make sure that you are using the recent Studio version of the driver, not the Game Ready version.

Another try is to enable the Older GPU Mode option in "Preferences" > "Technology Previews" > "Use Older GPU Mode (pre 2016)".

If this all doesn't help, we need more informations about your system. Maybe you can post your Photoshop system info. In Photoshop goto Help > System Info and hit the copy button. Then paste the entire informations into this thread.