> Given Steve Jobs' character, there may be another reason behind it: that year, before the decision to stop supporting Flash

Flash was never supported on iOS; Steve's letter was to confirm Apple wasn't ever going to support Flash on iOS; it remained available on MacOS.

I don't think the Photoshop thing had any affect on supporting Flash on iOS.

You're right, I did a quick search and apparently they still considered supporting it though [0], but they didn't they the results they were hoping for.

[0] https://9to5mac.com/2021/04/27/apple-tried-to-help-adobe-bri...