Vari-Bisexual is when one is both Varisexual and Bisexual. This can be due to experiencing shifts in sexual identity (.i.e Biflexible) or feeling fluidity in their Bisexual orientation (Bifluid).
Vari-Bisexual is a subset of Variqueer specified to Bisexuality. It can be seen as an umbrella term for identities like Bifluid, Fluid Bisexual, Abro Bisexual etc.
It can also be a way of expressing your identity is alternating, changing, and fluctuating without picking a label like Bifluidflux or switching between sexual labels to describe yourself if you're bisexual and experience your sexuality fluidity.