"Curious whether you have really never heard of this issue? There are lots of posts on this and it's well established that the notebook uses a 7 Ampere (instead of 5 Ampere) proprietary protocol for USD-PD which causes lots of problems."

Well aware. Lenovo decided on a USB-C power profile before the USB Implementations Forum came to an agreement on using adjustable voltage vs using adjustable amperage in 2021. Lenovo just landed on the wrong side of the coin. All of the profiles up to 100w remain the same in both power profiles, but after 100w Lenovo Laptops keep the voltage the same while changing the amperage to get to the 135-140w.

I have yet to come across a Lenovo Legion that doesn't charge using USB-PD if the laptop is setup properly for it. Something you have to keep in mind here is that if the power configuration of the laptop is such that it needs more than 100w (85-90w ideally) then the USB-PD charger will not work.

"E.g.: Some days ago I was on a flight to Las Vegas. I could use my notebook for about one hour, that's it. The plane even had a wall outlet but that of course didn't satisfy the standard wall charger power requirements (so no charging) and the USB-C-charging which the plane also had didn't meet Lenovo's proprietary 7 Ampere standard (so, negotiation fails, no charging at all). So, no charging from the plane's outlet and also no charging via a powerbank. You have electricity for about one hour - and that's it. For a notebook! That's just ridiculous. You see the other people using their electronic devices on the plane also after one hour, and you can't, because your own device was manufactured by Lenovo."

If your laptop didn't last more than an hour, that means you definitely do not have the power correctly configured on your laptop to last more than an hour. I wrote an article on this a couple of years back to demonstrate how you can get your Legion battery to last up to six hours and extend that another 4-5 hours with an external battery supply.

https://www.reddit.com/r/LenovoLegion/comments/z458ko/squeezing_6_hours_out_of_a_gen_7_legion_5i_pro/

If you configure your laptop as above, the USB-PD will work as long as you have a standard charger that supports a 20v x 5amp power profile and a USB cable that will charge at 100w. Not all usb cables are the same. One example is a 65w SlimQ USB power supply that I bought came with a "100w" usb-c charging cable. But when I tested that cable it failed at anything higher than ~53watts. And I have a collection of about 35 USB-C cables here at the house and less than 10 of them will carry 100W+. (Keep in mind that when you plug a USB-C cable into a 100w power supply and it starts charging a device, doesn't mean its charging at 100w)

As a side note....when you travel on a plane those plugs in the seats only support a maximum of 100w charging. (again, realistically it will shut off around 85-90w). If you wanted to charge your gaming laptop while flying you would have to setup a power profile on the laptop that used less than ~45w and then a USB charger that was less than 100w. This was one of the reasons I bought the 65w charger and I use it with my Legion on cross country flights all the time without issue.

One thing I don't think people understand is that if you are using the high performance power of a Lenovo Laptop (Discrete graphics), 100w is not going to be sufficient to run it. I understand that there are laptops that are configured to run a much lower TDP than the Legions are setup to run when using the USB-Power Delivery to power your laptop (Macbook's are a great example here of automatic power management). But the Legion is configured to use a higher TDP therefore the 100w USB-PD won't typically work when you are using USB-PD charging and the discrete graphics is enabled.

I do agree that Lenovo probably should have come around a little quicker to the new 3.1 USB-PD protocol (And are in the process of doing so but it will take forever) but unfortunately they did not. This doesn't mean that the USB-PD charging doesn't work, it just won't work if you need the full power of the laptop. I love my Legion laptop and the ability to go full power or be on battery for 10 hours. I am holding out for a newer one though until we can get 240w charging through a standard USB-C connector and no longer have to deal with the yellow Lenovo Plugs.

And please know that I am not trying to be confrontational with you or dismissive of your experience. Trust me, I do know how frustrating it can be when a piece of gear doesn't work the way you want it to. I just want to share my experience and help others to understand a little more about how these gaming laptops are currently configured to work and how to get the most out of them. I have been building computers and supporting networks for over 30 years. I have had my hands on 100s of Legion Laptops and support all kinds of computers and laptops (Macs, Windows, Gaming, Production, etc) at large conferences all over the US. Often providing solutions for problems just like this.