I'm 23 pregnant and was wondering can I use this serum on my face to spot treat my acne marks it has hydroquinone and retinyl propionate?

No. Retinol derivatives, like retinyl propionate, are recommended against for use during pregnancy due to the possibility of birth defects in similar compounds. It is best to avoid these types of creams and use something different while pregnant.
Better choices. The use of topical retinoids is controversial in pregnancy; oral forms of similar compounds can cause birth defects. Hydroquinone can be absorbed through the skin more than other compounds. Use benzoyl peroxide or topical Erythromycin for safer choices in pregnancy.