If it's signed and it's not just a "private land" sign, but explicit ban on other people being there, then ok.

The only sign I see on aerials is a sign near the playground and at the time you see it, you are already there.

https://fotoladu.maaamet.ee/etak.php?B=59.43295290801652&L=24.80795025799743&fotoladu

I think it's more important to change playground's access, as it's currently explicitly public.