Filip, I think you have worn out the brake band, that supplies 2nd and 4th, and the high clutch is slipping.
You say;
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This event was the first signs that the brake band was slipping to get worse. The band is applied to shift from 3rd to 4th, this leaves you with 1st and slightly slipping 3rd.
This section;
This bit I think you are slowing down in 3rd, to 2nd to accelerate away so the band slips till 3500 when the high clutch engages again. A bit hard to tell the change points as you have it in Economy Mode that will make it stay in the gear to lower road speeds, before it changes down, and change up at lower road speed. You would do better with that Mode turned off to reduce the load on the band and clutch.
So the way I see it happened was the band did a bit of slipping when it was driving in 4th, this wore it till it will not work for both 2nd and 4th.
I can’t see any signs that 3rd is not working, but, maybe slipping under load.
In this bit,
I think it was accelerating in 1st,, the change to 2nd happened, but the band slipped till 3500 when the high clutch came on with a bang, for 3rd .
I think a rebuild would be the best plan, they would use the upgraded parts, and you end up with a reliably transmission.
