I agree with this comment.
There is a difference between change and the acquisition or loss of information. Nowadays people imply that evolution is an improvement or acquisition of new information which is not necessarily the case.
From what I have seen most things do not become something else, they just become different versions of what they already are, and in most cases there is a deterioration or decay of information not an influx of new data.
Adaptation to a dark outside environment, leads to the species becoming darker to survive.
In the case of the virus a weaker virus means that the virus will survive, not that it is a better virus. If it was a better virus it would not only survive but at some point completely take over the host.
For a virus like Covid-19, the best case scenario (from the virus' point of view) is to remain just as contagious, but become less virulent. We are trying to eradicate Covid-19, but if it were only as virulent as ordinary cold viruses, no one would really care about it.
Only retroviruses have successfully "taken over" their host. They are RNA viruses that make a DNA copy of their genome and insert it into the host's chromosomes. About 8% of our human genome is actually retrovirus nucleic acid. Retroviruses are essential for placenta development.