Have done for decades. Senna, Martin Brundle, Michael Schumacher, Niki Lauda are some of the notable ones. It’s the bit of branding that’s theirs, not the team or the sponsor. It’ll follow them between teams and on to their next career too.

So they can sell their own merch.

Stroll apparently used his logo in 2016 already while Lando started using his own one in 2017..

Also, it is quite different because in Lance' case the letters are supposed to display a halfed "18" while Lando's shows the "4" in the negative space instead.

I posted this when the earlier versions were posted a few months ago

Yet still not as good as Lando's. Lando has his number (4) in the white space, Stroll doesn't (18).