Drivers may not touch the line at all.
Front tires aren’t, but a snap of oversteer caused the rearleft to touch it.
Jan Lammers said on Dutch television that if Max didn’t reacted, he would hit the Armco and nobody could pass. Which is dangerous and therefor Verstappen will not have a penalty for it.
I also agree, since Leclerc hit the pitentry line several times in Saudi-Arabia and nothing happened there.
On the other hand, wouldn’t be the first time stewards give a penalty to Max, and let others run away with the same or even worse action(s).
Can’t tell from this still, moving images give a better perspective.
From this picture I can’t see if the line ended here or not.
Edit: it is not over the line. Drivers may touch it.
This has been clearified since 2020