One way to be to evaluate how much compensation you could achieve from blood plasma donation. You could then donate the funds to charities addressing farmed animal welfare and consider whether those funds being donated has a higher net effect on farmed animal welfare than the harm you are causing by increasing demand for factory-farmed meat by resuming an omnivore diet, the benefit you are not generating by increasing demand for vegan products, and the benefit you are not generating by providing others an example of a vegan, thus helping normalize it.
One way to be to evaluate how much compensation you could achieve from blood plasma donation. You could then donate the funds to charities addressing farmed animal welfare and consider whether those funds being donated has a higher net effect on farmed animal welfare than the harm you are causing by increasing demand for factory-farmed meat by resuming an omnivore diet, the benefit you are not generating by increasing demand for vegan products, and the benefit you are not generating by providing others an example of a vegan, thus helping normalize it.
I don’t get compensated at all for blood donation/​plasma donation/​platelet donation...