I don't know what settings you are using for defending? Online is only supposed to allow in competitive - Tactical defending and Advanced defending.
Is this against PC players you are noticing this?
Console and PC players should not be able to use legacy defending online. Period.
Surprised legacy defending has not been removed from the game entirely.
How are you defending? Are you calm? Are you fanatic? Do you jockey? Do you keep changing to the CBs? How do you defend? Are you holding sprint down all the time? Because that will not help with defending unless you absolute need to.
Are you playing low block? Balanced or high line?
Give us some more insight in to how you defend...