First of all, I'd like to thank the talented engineers in Valve for bringing us awesome technical solutions and pushing the industry forward even despite having to comply with "efficient managers" who clearly got in charge of Valve somewhere around 2014. Guys, you totally rock! Looking at what you've done with Proton, SteamOS and Steam Deck, there's still a hope for gamedev industry. So here's just a bunch of observerations and thoughts on what could be improved, I don't expect much to happen, but it would be great if something would be actually implemented/fixed eventually.

• Being able to add games you own to a wishlist is a great way to keep an eye on something you'd like to gift to your friends, I don't know why isn't it allowed and there seems to be some sort of a validation removing anything you already own when you add something new even if you added it using some tricks.
  
• Privacy settings lack some fine granularity and don't cover everything a steam profile has to display. For example your avatar is always visible, badges and levels can't be hidden/downgraded, you cannot remove a featured badge, you cannot chose if you want to be displayed in a list of friends with highest steam levels on a friend's page if you limit privacy of your profile, you're either there if your profile is public and not there if it isn't, you could say it's expected since it kinda exposes your steam level which you kinda said to hide (well, there's no such separate settings, only your profile's overall privacy) and I could agree with you on that, not a big deal anyway. It would be nice to have ability to set privacy to all displayed sections separately, provided it actually works, there seems to be an issue when a private profile which has everything set to private/friends only still showing "Currently Offline Last Online X days ago", which clearly is not supposed to happen.
  
• There's a library game list issue, when you hide/unhide games or assign games to collections resulting in a game not being in a position it was and scroll resetting to the very beginning for no obvious reason, for example you were checking your games, categorizing or hiding games you don't want to see and all of a sudden scroll moves to the top and you have to find where you left off and it's not really convenient when you have lots of games in your library.
  
• Some "tools" you get when you have a certain game on your account are impossible to remove even if you remove corresponding game, standards procedue on gtm.you1.cn/helpsteam doesn't work for such tools like it does for normal games. For example: blazerush dedicated server.
  
• There's no way to get a list of games you "removed" from your account on gtm.you1.cn/helpsteam, even though if you remember a game you can manually restore it using its name, so some data on licenses is being stored somewhere for such games and I can't think of a valid technical reason it would be impossible to get such a list. I even remember contacting Steam support regarding such a list of games I technically have, but they're not in my library being manually "removed" from my account and support answered it's impossible to get such a list, well, maybe it's impossible for support staff to get this info using tools they got to help Customers, but I see no valid reason such a tool couldn't be implemented for Support or even a self-service "tool" on gtm.you1.cn/helpsteam where you click "show games I manually removed from my account" and you get the list, like you can do with boosterpack eligibility and so on.
  
• Also games you remove from your account that were "hidden" in your library will stay there for some reason until you "unhide" it manually, such games show "purchase" button instead of "play", I see no reason storing hidden state or such games if a player decided to manually remove this game from their account.
  
• There are filters in game library for let's call it a "content-type": game, soundtrack, tool, software, etc, and these filters have numbers of content currently filtered, but it only works for conent which isn't hidden, for example I don't want to see tools, soundtracks, etc in my libarary, only games, so I hide everything else along with games I don't want to see, but when I switch to hidden games in my library filter values remain the same they are for my library games, so I have 0 soundtracks, 0 tools in my library and when I switch to hidden content which has all the soundtracks, tools and so on filters still show 0 tools, 0 soundtracks displayed, even though filtering itself works correctly, it's just inconvenient when you want to get a total number of something and you can't use filter numbers so you have to count it yourself somehow instead.
  
• Some showcases seem to be glitched, for example I somehow can't feature year review as a showcase even though I checked game review when it was available and have that badge, also additional game collector (points shop purchase) showcase while being upgraded using steam shop points to level 3 keeps resetting its size each time I unfeature it on my profile, resetting games it used to have, which is a bit annoying.
  
• Downloading summary message in the bottom of Steam client isn't clear enough, currently it says "Downloading x of y", and what x and y actually are is rather hard to say, e.g. I have 1 game already downloaded and 2 more games downloading, it says "Downloading 2 of 3", but if I have 1 game already downloaded and 1 downloading, it says "Downloading 2 of 2", isn't it kinda confusing what it actually means? It would be more helpful if it said "Downloading, x out of y done" where x is a number of games successfully downloaded during current session and y is a total number of games in downloading queue during current session.
  
• Marking games as private is a great idea and it resonates to having some fine-grained privacy settings, but it would also be a great idea to be able to set wishlist items as private.

P.S. there's no point in having a discussion about this since it's only intended for Steam developer, but feel free to have your opinions and comment, I just wanted to let you know that I'm not going to check out this discussion after it's being posted, so don't expect me to answer.