Flutter freeze on older iOS Devices (regression)

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Dear Flutter Community,

   I hope this is the place to post this, if not, that would be very appreciated if anyone could point me in the right place to post this kind of question. :)

So, I've developed an application using Flutter for many months/years (started around fall 2018 and developing on and off since then). I've used it internally and with multiple clients. Now I want to publish it to the App Stores, so I want to use the latest Flutter Stable version. However, since last Fall, I'm stuck at Flutter version 1.23.0-7.0.pre since this is the latest version that would let me run Flutter smoothly on old iOS devices (tested on iOS devices that are stuck at iOS 9 and 10; on my side, tested on: iPad 2, iPad 4, iPhone 4S).

If you want more information, I've sent a bug report around 2 months ago to Flutter's Github page here: https://github.com/flutter/flutter/issues/78507

I'm not getting any answers there and since this is a regression that block the use of Flutter on older iOS devices, I would think I'm not the only one in this situation and feel that many would be more verbal around the Internet if this was a global problem since this is quite a major performance problem... 

Therefore, does anyone stumble into this problem on their old iOS devices? If so, did you find a workaround to make Flutter work? Or does anyone have any idea what could be the problem and if you have any idea for a solution?

I've tested yesterday with the latest Stable version and Master version and I'm still having the problem.

I'm loving Flutter and wish to put this behind to move forward! But at the moment it's not very reassuring to stay at version 1.23.0-7.0.pre

Thanks anyone for any help! This is really appreciated!

All the best,

   Guillaume