Even if broadheads are true, the insert of the arrow could have a face not perpendicular to axis.
G5 makes the ASD (arrow squaring device).
Have seen inserts brand new that needed cleaned up, and others that took a hard hit, that needed redone.
Still not a common ailment, but does pop up now and then.
If you have a funky arrow w BH, might want to check that insert face.