Interesting information. Soviet Union tried to press YLE to limit the spill over signal to Estonia. They even planned to construct a net of metal in the Gulf of Finland to stop the signal. Today, a valid agreement regulates the distribution of the spill over signals.
Anyway, for me this is not the case. When staying in Finland i expect to get the due service from the terrestial provider. I don't need to feel any bad conscience because I pay for it.
The fact is, that the T2-signal of my nearest subsender was strongly decreased. The reason is said to be a change in the operator's license in the network. It is not known to me what this means. I directed my antenna to the main sender, much farther away and only a few degrees beside the subsender from my place. T2-signal there has the same frequency. All the signals have now full strenth and all the channels are spotted without any problems. This was, of course, very confusing before I realized it. I regret if any peace of mind has been stirred by my speculating with any possible firmware or software problems.
So, all is well now and the case is closed.