I have just come across this thread while searching for a solution to this exact same problem but on my iPhone iOS 18.5 (22F76).
It seems that, as of June 17 2025 this still hasn’t received any attention from Apple 😞
I have come up with, a rather inelegant, WORKAROUND, that so far is just about manageable.
I have set up two automations:
- one to enable my desired focus upon the opening of an app,
- a second one to close down the focus when the particular app is closed.
As things stand at the moment, putting the triggering app into background mode so triggers the focus to close down. This can be averted, however, by ensuring that “Run After Confirmation” is selected for the close automation, and then ignoring the prompts each time they appear. Until you do actually want to close things down, of course.
I must admit being somewhat surprised that Apple hasn’t addressed this over the past 2+ years. Shortcuts and Automations, used in conjunction with the Focus function, is a powerful bit of capability and something Apple has done really well in recent years. It’s a little strange that something as mundane as this issue hasn’t been fixed. It makes me wonder if there are unforeseen consequences that maintaining a Focus, while an app is in background mode, causes.
I am now going to enter a ticket on Apple’s official ‘feedback’ forum. Hopefully I’ll be able to log it against the entire Apple ecosystem, rather than it being limited to just the iOS section.