There's so much hyperbole in what you wrote to support, I find it difficult to even know where to begin. But even with you being nice enough to quote it in full, I want to say this:
Is it true that Galaxy 1.2 has features Galaxy 2.0 is lacking? Yes.
Is it true that basic functionality some users require to operate are present in Galaxy 1.2 and missing from 2.0? Yes.
Is it true that Galaxy 2.0 has had a known glitch since it was still actually being properly treated as beta which makes even GOG games, let alone ones from other platforms, disappear from user libraries in 2.0? Yes.
Is it true that the last thing isn't a problem with prior versions of Galaxy? Yes.
Is it true that Galaxy 2.0 became a forced auto-update during the current pandemic? Yes.
Is it true that prior to the abovementioned decision, support was already quoting a 4 week turnaround time on tickets? Yes.
Where is the "hyperbole" in pointing facts out? Seriously, nothing I'm saying is anything other than a blatant and easily-verifiable fact.
If you have to resort to yelling (all-caps on the internet), then your feedback is inherently nil and void. You will get listened to, you will get smiling faces and "Of course, sir", but everyone will forget you the moment they turn around, and make that as much of a priority as they can. You're annoying people who merely do their job, and for no good reason, they've not done anything to you.
I used a web form in my initial contact, and I sent emails in plain text without formatting functionality. Please explain how ELSE I'm meant to be adding emphasis in plain text without impairing readability more than all caps does? Pro-tip: THAT IS A RHETORICAL QUESTION. I frequent a wide variety of sites which use a wide variety of formatting functions, and when I'm regular enough using one to bother getting used to its specific formatting functions, I will sometimes use them, but capitalisation (or lack thereof) is always going to be a valid method of adding emphasis in any text-based format. If you don't undestand that, I'm not the one being immature here.
And as was mentioned by a previous reply to your comment, after more than a month of waiting without a reply, to a support ticket following up a prior support ticket which had also been more than a month without a reply, and has now been two months without a reply, and which itself had been a follow-up to a support ticket that took over a month to get a reply after having been promised a reply within a timeframe of less than a month, I think I'm a fair distance past the point where venting a little frustration by HOLDING MY SHIFT KEY WHILE TYPING is at times justified.
Plus, honestly, it just sounds ridiculously immature. When was the last time you did that IRL? Or are you maybe one of those dreaded individuals who walk into a shop and go "WHAT YOU'RE DOING HERE IS TERRIBLE YOU'VE WRONGED ME IMMA SUE YOU BECAUSE THIS POODLE JACKET IS BEIGE AFTER WASHING INSTEAD OF SAND!!1!!!eleven!one!"? Because if you are then fair enough, at least you're being consistent. But then you also have to realize that this is the type of behaviour children usually display when they get their toys taken away, it is crying and whining merely in the hopes of getting attention because hey, that worked with mommy and daddy!
The last time I shouted at an employee in a store? Well, that was a few years ago, but it certainly took less than 6 months of not getting a valid response to constructive feedback about a serious mistake being made by the company before I reached that point.
In case you actually care, it was at a restaurant, after I had placed an order and paid for it, when I received several items I hadn't asked for. I started, as I did with GOG, asking politely why this had happened. When I didn't get any kind of apology, or suggestion for how to fix it, WHICH IS HOW I WAS TRAINED TO RESOLVE CUSTOMER SERVICE ISSUES, but was instead told flatly and without any hint of consideration, "what you asked for was sold out so we made this instead", I pointed out that I'm NOT ABLE TO EAT the food they had replaced my order with. I still wasn't raising my voice, but I WAS adding emphasis to that fact by speaking through clenched teeth. Instead of handling THIS comment with an apology, the person walked away, without telling me what they were doing, and I was ignored by another server who I asked what was going on. The manager came out, and tried to tell me, in spite of my receipt showing the items I had actually ordered, and those items not matching my order, and the person who served me having told me otherwise, that I was lying about what I ordered to get a refund. THAT is when I raised my voice, and doing so is what got me the refund I had every right to insist on at that point.
In this case, I'm not asking for - and have no reason to expect - a refund. But I am being appropriately upset about a situation which is being handled poorly, and has been getting consistently handled poorly for far longer than it should have been. I am NOT directing my anger at the customer support staff to whom I have been speaking, and as someone who has worked the majority of my life in customer-facing positions, I know that most people with such jobs can tell the difference between a customer who wants their frustration to be shown and passed on appropriately, and one who is raging without valid reason, REGARDLESS of whether the customer is doing so by raising their voice, typing in all caps, or otherwise.
So yes, I've got a load of problems with GOG Galaxy 2.0. Nevertheless, how you act in fact makes me like the new client more, just because it hopefully means one more person who can't act civil around support or sales people won't stick around.
As long as GOG is a valid storefront providing good products at good prices and DRM-free, I'll be sticking around here. Regardless of the problems I have with Galaxy 2.0, I still have the ability to use Galaxy 1.2 and if that ever fails, I'll still have the ability to play my games without needing to run them through any client software. The failings of this mess of a client, while they may discourage me from spending as much money here as I otherwise would, aren't going to negate the value of this storefront for me.
This is far from being as bad a problem as Steam's past year of seemingly-deliberately screwing customers over.