I'm no Tesla fan, but while this may have been true years ago, I don't think it is any longer. In 2021 (haven't seen 2022 #'s yet), Tesla sold about $1.5B in carbon credits. In 2021 Tesla had ~$5.5B in profit off ~$53.8B in revenue. (source). So in 2021 the credits were about 3% of all revenue and about 28% of profit. Significant for sure, but it sure seems like the bulk of their revenue and profit comes from selling cars.

Also, I wouldn't call carbon credits a direct subsidy. Tesla (or any company) gets them from the government for free. And then sells them to other companies. Outside of government administrative costs, the "taxpayer" does not pay for the credits. The consumers of the companies who buy credits ultimately pay the cost. There are other direct subsidies for EVs, e.g. the direct consumer tax credits.