Again, the topic I started is how temporary app remowal works.
So far, you helped by confirming this feature cannot be triggered manually, but only automatically by iPhone if there is enough free storage to run this operation, prior to installing the new update. Thank you for that.
Building on that, I conclude there is no official manual, statement, or description of how this feature works nor what are the conditions to have it automtically triggered.
I can only share woth the community my recent experience, from last night. With my free storage below 10GB, I got numerous notifications about an overdue update, but the Temporary App Removal was not triggered. As soon as I made free sligntly above 10GB od space, Temporary App Removal option was offered, and it enabled update installation although the phone required 13.29GB to perform the task. This brings me to a practical conclusion that minimum free space needed to automatically trigger Temporary App Removal is 10GB (or slightly more) and that maximum storage it can free up is around 3.5GB. This may of course depend on what kind og apps you have installed, how many of them are offloaded, how frequently you are using each of them, etc.
Would love to hear if anyone has any official confirmation about this presumption above, or could share a detailed experience of how this feature worked for them.
Please no off-topic advice.

