Read the bill, my dudes. Well, first with the understanding that this is unlikely to pass as it's currently drafted. But given that, here's the details: (starts on page 50)
-Transition period: point where a manufacturer hits 200k plug-in vehicles sold in the US.
-Phaseout period: 2nd calendar quarter after the point at which a manufacturer hits 600k plug-in vehicles sold in the US. (50% credit for the first calendar quarter of the phaseout period.)
-Exclusion period: period from which a manufacturer hit 200k and the passage of this act.
Vehicles sold during the transition period are able to claim the credit less $500.
Vehicles sold during the exclusion period do not count.
To say it more concisely: yes, this will harm Tesla as it still relies on a per-manufacturer cap, which Tesla will hit way (way, way due to the bigger cap) before anyone else. But it would reinstate the credit for Tesla until they hit 600k + [number sold since they hit 200k and the passage of this act] vehicles sold in the US.