TLDR: Duh. Shimano has been this way since the pandemic started and it won't get better anytime soon. MSRP will be the prevalent pricing strategy for the foreseeable future. Days of cheap Shimano are gone for at least 3-5 years.
Oh FFS. "suddenly they are difficult to find"?!! Really? Suddenly? Where have you guys been?
I've been selling my soul for over a year to get ANYTHING Shimano. I have a friend who is building a Dura Ace Di2 build because he scored an SL6 frame cheap on clearance last year. It took 5 months to get the hubs from Chris King. I told him to scour the internet for parts as through Shimano my delivery dates were June (this was last September) but I told him to check to make sure they actually had it in stock before trying to buy it. I get his wheels built and check in with him - he was still waiting on parts. 2 weeks ago I sat him down and we scoured the internet for the last 3 or 4 parts. Took 3 hours and involved some phone calls to verify the item was actually there and not just listed as in stock on their website.
Here's the deal guys - Shimano also had to shut their Malaysia plant down last week because of Covid. They can't get containers to ship. They were woefully out of stock in the US for years leading up to this. They couldn't care less about "aftermarket" parts as their entire business is OEM. Their OEM orders are 3 years out at this point. Last year they wouldn't put an OE order in unless it was for at least 1,000 kits and even then they were saying "maybe 8 months".
During all of this all of the online places that were buying grey market product and flipping them online at US wholesale prices dried up. The ones that didn't realized they were idiots for selling below MSRP. Guess what? The days of easily paying below MSRP for a genuine Shimano part are over for the foreseeable future. How is this forum just now figuring this out and so late to the game?
If you have stock of Shimano disc brake pads for road groups with fins you will find you can sell them on eBay for twice what you paid for them. If you enjoy riding and didn't stock up on parts already then good luck.
As for Ultegra 11 chains - I myself have one in desperate need of replacement. Even as a bike shop I am now going to have to switch to Connex/Wippermann. I still have a small stockpile of KMC OE chains I got a few years back but they tend to be on the short side for road use and everyone today wants to run huge cassettes so they can go slower.