You can ask your former employer to help you out with more money, but assuming you weren't under an employment contract, they aren't required to offer you severance at all. Your only recourse would be to quit, which probably won't make them change their mind since they're already terminating your employment...

Since it appears you work in California, file for unemployment immediately and apply to new jobs.

Is your total income $33901 or $47954 ($33901 from spa and $14053 from serving job)?

Your issue probably stems from not filling out the multiple jobs worksheet on your W4s for both jobs. They both think they're your only job so don't start withholding taxes until $12950 (standard deduction) resulting in double counting of the standard deduction.

Do you have enough cash on hand to pay cash? Or are you looking to finance the full amount?

If you only have $1k left over, you don't have room in the budget for much. I live near you (I assume, based on your username) but make about $10k less in take home per month. I bought a new Toyota Highlander Hybrid 2 years ago right before the supply chain issues and interest rates skyrocketed, and my payment is $775/month at 0.9%. Nowadays the same car will cost $5-10k more at 5-6% interest. Add in gas, insurance and maintenance and you've already eaten up your extra $1k.

I would spend a couple months tracking your budget on exactly where the extra $8400/month is going (I know it goes quickly, probably $2-3k on groceries and eating out, $2-3k on furniture/stuff for the house, etc.) and what you are comfortable dialing back on to make a new car fit in the budget.

That's not true. The IRS specifies in the Fringe Benefit section (Pub 15-B) in multiple places that commuter benefits must be used only between your place of residence and your place of work. Use for non-commute purposes is not eligible for pre-tax treatment.

Highly unlikely the IRS will ever investigate an individual for the minimal difference it might make though.

A commute is, by definition, travel between one's home and workplace. Your home and workplace are the same, so I doubt you incur any public transit expenses worthy of commuter benefits. A commute does not include workplace errands or travel to locations you'd prefer to work from (if anything, your employer might reimburse you for work-related travel expenses). You could probably make a case for using it to travel to co-working spaces provided by your employer.

But as many people have pointed out, enforcement is an extremely unlikely possibility. And worst case, they're just going to ask you to pay taxes on the benefit. So if you are willing to take that risk, just sign up for/use the benefit.