It peaked at 4.05% in March. The last 2 months it went just below 4% as the Unknown category increased. For June the reverse happened, so 4.04% seems to be the real current share of Linux on Desktop as desktop clients were read properly/werent spoofed.
It’s still useful with all its functionality. Even if it does not get updates, it still blocks most stuff and I can enable or block stuff too. Plus the blocklists it uses are still updated, as they act independently from the main addon. There is no better alternative in my opinion. I use uMatrix + uBlock Origin.