These deadly attacks are a ‘sign of desperation’ as Putin is realising he might not win the war.

Pure speculation. There is nothing to substantiate the claim that Putin is beginning to realize he may not win.
Of course he should be realizing it, but the statement is pure speculation, there is no real change in what Russia is doing compared to what they’ve done so many times before.
The strikes in civilians continue as they’ve always done. And are probably meant as retaliation for the attacks on Sct. Petersburg and Moscow.

But Russia is collapsing, their infrastructure and economy is collapsing, so maybe Putin is no longer able to deny the facts. It’s a fair enough assumption, just no based on what they claim to base it on.