He was the target. Allegedly reported in Israeli media (I don’t have a link), but the strike was a “surgical” (I hate the term) strike on the specific apartment he was in, not just the entire building like they so often do.
When pressed about it, Israeli propaganda will point to a joke he made on Twitter about the fake “baby in an oven” atrocity propaganda story, mark my words.
https://euromedmonitor.org/en/article/6014/Israeli-Strike-on-Refaat-al-Areer-Apparently-Deliberate
He was deliberately assassinated. This was not “collatoral damage”, well, except for his brother, sister, and the four children.