You're misunderstanding how long term capital gains (LTCG) are taxed. $80,250 is the taxable income threshold for the 12% tax bracket (Married Filing Jointly). Your ordinary income, e.g. wages, go in the 12% bracket, not your LTCG.
Using an example: you have $50,000 ordinary income and $75,000 net LTCG. After applying your standard deduction ($24,800) you have $100,200 taxable income. $25,200 (50,000 - 24,800) ordinary income will be taxed at 12%.
$55, 050 (80,250- 25,200) of your LTCG will be taxed at 0% and $19,950 (75,000 - 55,050) will be taxed at 15%.
