I try to remember the exact build that tried to start to update links immediately when the changes happened... If I refuse to update (and sometimes there’s a reason for this), I started to get constantly bombarded with 'Some files are missing or modified, would you like to update?' ...no, I say. But each time the app gets focused, I get the message again. Sometimes the frame doesn’t get loaded after some work outside (and can’t get updated because of this dialog that gets retriggered while I try to make Ai awake).
It doesn’t really match the problem with instant update you mention, but I think relates a bit.

Update (2026年7月):
This issue is still NOT fixed. I've now confirmed it also occurs in Illustrator 2026, not just 2025. Environment: macOS Sequoia 15.7.5.
I did more detailed testing and found the exact timing pattern:

If I do nothing after switching back to Illustrator, the link-update dialog appears automatically after a fixed ~30 seconds.
If I click on any object on the canvas after switching back, the link panel's yellow "update available" icon appears after ~3-5 seconds — but no dialog is shown.
Toolbar interactions alone do NOT trigger anything.
If I switch to another app/Finder/desktop and then back to Illustrator, the update dialog appears after ~3-5 seconds.

This consistent, fixed timing (not random OS-level delay) strongly suggests this is an internal polling/event-handling regression in Illustrator itself, not a macOS issue. It's been over a year since I first reported this — could someone from the Illustrator team please confirm whether this is a known issue and if a fix is planned?

PNG and JPG files show the same issue as PSD.
The 29.8 build has not yet been released to me, so I cannot test it. I normally don’t use Illustrator Beta, but I installed it just now to check, and the result was the same.

In all cases, when saving again in Photoshop and switching immediately back to Illustrator, the linked image does not update. After a few seconds, a yellow warning icon appears in the Links panel, and I have to manually update the link.

After further testing, I found that if I wait about 5 seconds after saving in Photoshop before switching back to Illustrator, the link will auto-update correctly.

So the behavior is:
• Save in Photoshop → switch to Illustrator immediately → no update (yellow warning icon appears, manual update required)
• Save in Photoshop → wait ~5 seconds → switch to Illustrator → auto-update works

Restarting Illustrator and resetting preferences did not resolve the issue. This behavior never occurred in Illustrator 2024 or earlier.

Hope this helps to reproduce the bug.

Haven’t heard about it yet...
Does is happen with PSD files only? What about PNGs or something else?
What about the 29.8 build that has just been released (it might not appear yet in your CCD, it gets published in waves)?
What about Ai Beta?