Toggle Auto-switching to Photoshop

This is even more annoying. It normally (but not ideally) switches to Ps after "Open as Layers in Ps..." but when I go back to Lr, it then it switches to Ps AGAIN! (after is done opening the images). It started about 5 days ago, my lasts updates to Lr and Ps was over a 9 days ago. MBP M4 on Sequoia. It normally stays in Lr after switching back from Ps.

Ok, I missundersstood

However one of our macbooks does NOT switch over to photoshop automatically which is extremely helpful because we can open multiple files and then switch over to photoshop once we have opened all the files we want to work with.  We want to figure out how to set our other macbooks to not autoswitch to photoshop.  

You do not want to switch over to PS automatically??

I see I have issues in understanding, so I will state the below normal workflow..

• The photographer selects multiple photos in Lightroom Classic.
• The photographer right clicks on one of the photos (most likely whatever one of the group is already selected)
• The photographer selects Edit In
• Then selects Open as layers in Photoshop
• Photoshop opens with the selected images
• The photographer accomplishes the desired PS edits, and either Closes, or Saves, the work
• Lightroom Classic comes up to front again, and the PS created image appears along with the originals.

Now, are you saying in your case for some of your computers: ??

• The photographer selects multiple photos in Lightroom Classic.
• Photoshop launches

On the problematic MAC, bring up /preferences/external editing/

Actually I do not think that is the issue after reading your problem again (dang it David, read twice, answer once) However, if the MAC does have that bit grayed out, that is another problem.