Screen flickering then freezing when logging in, No hardware issues found

So just to update - it is mostly fixed now when I changed the Input source to USB-C for the MB Pro on the Dell's Monitor U3419w.

This was previously set to HDMI through which MB Air is connected. I am not sure if this would happen on the MB Air if I connect it via USB-C and then choose HDMI as the input source.

Feel like this has to do with USB-C being treated as the primary connection source but then not being selected as the input source. Still not sure why that'd be an issue.

Overall, after making this change, I am not seeing any more of that flickering issues (at least for now) although the laptop keeps trying to wake up when on sleep, and unless I don't unplug it the annoying waking up sound doesn't stop.

Played around with the 'prevent from the automatic sleeping option' in display settings - no joy!

Hey Grant,

So today when I unplugged while the lid was open and the screen was mirroring, it happened again. Restarting resolved it. After which I unplugged several times with lid-closed, open, and screen-mirrored but no issues.

Is it because I leave it on sleep for a good few hrs and come back to it when something snaps?

Next, I will try to unplug it after a few hrs of it sleeping as you suggested i.e. Login and then put in on sleep from the menu... but I doubt that will make a difference.

It's a bit weird because on the same screen MacBook Air connected with HDMI doesn't do any such flickering after unplugging multiple times in different ways - which is a bit more bothersome as to why this specific system does it.

Thank you, Grant.

That makes sense but is there something I can do about it when unplugging? Maybe turn it on then unplug it? Or should I just live with it by restarting everytime?

I feel like it happens when the lid is down and I unplug it.

I have to sometimes use it when not at desk so unplugging is inevitable.

Also, I am not sure if it's relevant but sometimes when I close the lid, turn off the monitor, and leave it keeps making a wake-up sound / or when I plug it in sound every few seconds as if it's waking-up or trying to.

It won't go away unless I remove the cable or log in and put it to sleep again - sometimes it still happens and I have no choice but to just unplug it.

I've tried playing around with different settings but no joy. I am thinking to use a different cable to connect it to the monitor.

I am going to try that next time and update here.

Thank you for your help, really do appreciate it!

Haha, no that's okay. I just unplug it when I go to some other place to use it or even in a different room than the home office one in a more relaxed sitting. If that makes sense. 🫣