Construction costs are currently skyrocketing

Unfortunately, you are describing two opposing effects here. If everyone rushes to existing properties, then prices there have to stay high with a constant supply. The price for existing properties can only fall with increasing demand if the supply is massively expanded. But I do not see that.

The first effect, which is really easy to observe – a lot is currently being thrown onto the market or is becoming visible on the portals. This also includes a lot of old stock, with major renovations. And also the "young used", something from after 2000. Just repaint and done. So the supply is noticeably increasing.

At the same time, we probably agree that there are considerably fewer buyers today than in January 2022 or last year. Many are simply "out". BTW: before the turning point, all objects from every class were gone in the shortest time.

What is still questionable – do sellers and buyers come together, and what price results then? The prices asked are often completely off track. They then stick for months, hoping that someone simply has the million in cash and wants to buy a run-of-the-mill house with it. Similarly, houses that are now actively being built for sale, full of compromises & prices that simply no longer fit today. If building itself is no longer affordable, who is supposed to pay the investor his margin? I find these objects particularly interesting.

Otherwise, prices are visibly falling, especially for renovation stock. There, offer prices already drop by around €100,000 after some time.

Or the expectations have to be scaled down again. You can also live well on 110 sqm with 1 to 2 kids without controlled residential ventilation and KNX. Or even with 80 to 90 and an expansion reserve in the roof. Maybe you just have to contribute a little more own effort again.

Or they simply eat cake when there's no more wheat for bread? Solutions can be that simple.

So nothing is selling at all in the existing stock right now.
I’m watching the portals very closely and what I’m seeing more and more often are properties marked with "new price!".

The days when astronomical sums were paid for really any junk and partially also for semi-decent properties are now over.
That is my firm conviction. Because for the broad masses (however one defines that, I’ll just say household income around €5,000) it simply is no longer affordable.

Recently been in contact with a real estate agent. His firm conviction: Everyone is now rushing to the existing stock because building a) is no longer affordable and b) is no longer predictable. I can’t see that at all so far. Especially since there were/have been hardly any building plots in the region anyway.
I think people who simply can’t afford it anymore also can’t rush to buy existing properties. The correction will come ...

Exactly. Cash is king again right now, but you still need patience.
There is a world of difference whether you have to finance €500k (+/- €200k depending on the region) for a standard single-family house at 1% or at 3.5%.
Of course for the broad masses, but unfortunately that affects 80% of the eligible persons.
A €1,400 monthly payment instead of €2,600 is worlds apart.
One can still handle the first with a good salary, but with the latter the risk of default increases drastically – "dual-income calculation."

Here with us here in RLP too. Every day many new offers come into the real estate portals. A year ago, there was nothing available here. What I don’t understand, though. Where do they all go? If I sell my house, I need something new. Do they all rent then? I don’t quite understand that.

Where are they all going? When I sell my house, I need something new. Do they all rent then? I don’t quite understand that.

Well, I actually suspect that not significantly more people want to sell something, but rather that not quite as many potential buyers are coming along, so the items stay in the portals a little longer. From the private environment, the reasons for sales are rather diverse: divorce, need for care, partner passes away, job change at a new location, or moving to a new place after retirement. Accordingly, "what comes after" is also rather diverse (nursing home/rent/new ownership adjusted to new circumstances/moved to someone else in rent or ownership/and uh... underground). Personally, I don’t know anyone who now wants or wanted to sell "quickly, quickly" out of fear of missing the opportunity, but my sample is also rather small ;)

Well, I actually suspect that not significantly more people want to sell something, but rather that not quite as many potential buyers come across it, and therefore the items stay on the portals a bit longer.

And that objects cannot be sold immediately at the seller's desired price within the circle of acquaintances, without ever appearing on a portal. Now suddenly quite a few things appear publicly that were previously transferred quietly.