Your 3D model’s axes are inverted on a tablet usually due to mismatched coordinate systems (e.g., Y-up vs. Z-up) between the model’s creation software and the tablet app, or incorrect display orientation settings in the app.
Coordinate systems define which axis is "up"—many desktop 3D tools use Y-up, but some tablet apps default to Z-up, flipping the model’s orientation. App settings like auto-rotate or axis inversion can also cause this.
If adjusting the app’s axis or orientation settings doesn’t fix it, try re-exporting the model with the tablet app’s coordinate system specified (e.g., Z-up for most mobile apps) to align the axes correctly.