Thuja are dying little by little

Are only the thuja affected or are other plants also dying? I suspect care errors. Too little water or waterlogging, too much or too little fertilizer.

Thuja is cemetery ;) not yew.

Only the privet is somewhat evergreen. The rest are therefore not alternatives.

What do you understand by evergreen? For example, the beech is also relatively dense in winter, as the leaves are only shed shortly before new shoots in spring. Thus, it always provides good privacy screening, although the leaves are brown.

Ligustrum Atrovirens works similarly there. Honestly, Thuja gives me the chills quite a bit too.

They are all poisonous anyway, more or less. Hedges are not for eating.

what do you understand by evergreen? For example, the beech tree is also relatively dense in winter because the leaves are only shed in spring shortly before the new shoots. Thus it always provides good privacy screening, but the leaves are brown.

Well, evergreen, the name says it all. On the one hand, I want privacy screening, but on the other hand, I don't want to look at brown leaves or bare branches. So I want green in the garden even in autumn and winter.

Amazing how everyone always has something against thuja, the same with cherry laurel. Better a green hedge than a fence.

You're right. But thuja is often used for cemetery planting... some development plans or design frameworks prohibit them because they cause a lot of darkness on the other side and also tend to grow very large (if you don't keep trimming them constantly) - this simply doesn't fit most manageable plots in new housing developments. Older terraced and single-family house plots now suffer from the older thujas. Consequently, a tractor has to come to pull out the massive trees.
They consume an immense amount of water because they are actually not of European origin, so they are not really suitable here.
It is known that hedges should not be eaten, but try telling that to the animals confronted with the cuttings that people do not pick up after pruning.
And: where there is light, there is also shadow: the density of the hedge prevents any light from reaching the other side. The consequences are meager perennial beds behind it or mossy lawns. Additionally, the density of the hedge attracts property crime.
Ideally, one uses a loose planting or occasional shrubs that lose their leaves and thus provide a light balance.

We were told elsewhere that they must stand one meter away from the boundary.

... because the distance has to do with the height.

I guess the soil is too alkaline. As far as I know, these plants need Epsom salt.
Perhaps the wrong fertilizer was used in planting? The greenery does hold up for a while. Yes, and then the immense water consumption. We're not talking about watering for 10 seconds...

Ultimately, everyone has to decide for themselves what to plant in their garden. Better a garden area than no garden at all, in my opinion.