New window between frame and wall very cold. What to do?

We have installed a new window in the kitchen of our house from 1989 (30 cm hollow brick wall). The window has an installation depth of about 6 cm from the outer edge of the wall. It was thoroughly sealed all around with window foam (approved for installation according to RAL). The transition between the wall and the window frame on the inside was additionally sealed with an acrylic joint. I am aware that this does not meet new building standards. Now, in winter, we have very cold temperatures at the transition between the reveal and the window frame. I took images with a thermal camera, see pictures. What can I do? It was actually well foamed. Should I attach a sealing tape on the inside between the window and the wall and then cover it with a strip? Or what else is possible?

Well - expanding foam is air-permeable, which is desired in existing buildings. If you don't have a ventilation system, the replacement is intended...

Windows are installed with three sealing layers.
On the outside, they are rainproof and vapor-permeable, e.g. with [Kompriband] or foil. You have not described this layer; how is it done?
In the middle, they provide thermal insulation, in your case with foam. This must of course be done properly, with good PU foam and not just anything. The foam is also not meant to "fit" windows that are too small – this could be a point here? The same applies to the [Kompriband] "outside"...
On the inside, vapor-proof with foil. Acrylic is cheap but possible.

I speculate that the windows are too small, and the insulation with foam should bridge this. Possibly, the quality of the window profile is (additionally) simply not good, which can also be guessed by the cold spots in the middle of the window.

As the picture looks, there is no thermal break at the bottom of the windowsill area. The cold penetrates through the windowsill into the house.

Nowadays, nothing is foamed anymore. Compression tape and internally breathable window connection tape, which is then plastered over.

I no longer install windows with foam. The compression tapes are now available in all sizes. Better for insulation, air circulation, and soundproofing.

You probably also have a poorly insulating window profile. What do you want to achieve here retroactively regarding thermal insulation?
I only see the possibility of doing something in the outer reveal itself, for example with additional Styrodur insulation.

To say something concrete, one would have to see the reveal from the outside.

Normally, nothing is foamed nowadays. Compression tape and breathable interior window connection tape that is then plastered in.

Nope, you can foam, even according to RAL. What's important is an airtight connection tape on the inside and a diffusion-open, rain-tight connection on the outside. Over 50% of the new builds around here have foamed windows, no compression tape; you can easily tell during shell construction, even from some distance.

If that were the reason, my window frames would also be ice cold, especially on the west side, where the cold wind pushes against them. That's not the case.

Foam is sometimes even better because for compression tape, the cutout must fit precisely and be plastered before installation. Because it doesn't fully expand into the lifting handles of aerated concrete blocks or the grooves of Poroton. Then you have a perfect thermal bridge.
Nowadays, when everything is slapped together quickly, the risk of errors with compression tape is much higher... better foam without major errors.

That is not true in such general terms. In the reveal, a smooth finish (with a light mortar) is sufficient, and if you buy the right tape, it expands up to 45mm. This also fills unevenness. But it is true that foam can also be RAL compliant and that you should preferably let a craftsman do what he is experienced at (as long as it is technically okay).