Hi there, as you can clearly read on my post, I have posted the problem I had as well as a solution myself - which might help others in the community.  Thanks.
I am writing this post so it might help others. I am describing the problem as well as the solution. Problem: All of the YouTube videos take about 5-10 seconds to load up before the playback actually starts. There will be a message "If playback doesn't begin shortly try restarting your device" displayed on the youtube playback panel. I have done all the suggestions posted in community pages referencing the drivers update (Audio, Video and Graphics), however none of them worked. I have also tried with different browsers and with all the extensions turned off. Solution: It seems like there is a bug (either with Dell XPS or with Windows 11) wherein the Youtube videos lag after connecting to a wireless display/cast. Once you try and connect to a wireless display and disconnect it, the playback will lag no matter what you do. So the only solution is to remove the wireless device under the devices section in settings and the problem instantly goes away! I hope Dell would identify this issue and fix it. Thank me later!   
YouTube playback delay in XPS 13 9310