Saving JPG from clean PNG adds jagged lines? [iPad]

[Veeta]

Hi,

when I save PNG as JPG, it adds strange jagged lines across the JPG. (Photoshop and PS Express on iPad ) It never happened before that. How can I fix it? PNG is clean and I’m saving JPG with the highest settings. I'm using iPad Pro mobile photoshop and photoshop express latest versions. Thank you

[Stephen Marsh]

Please provide the PNG or a crop of a problem area of the PNG.

Are you using Save As, Export As or Save for Web (Legacy) to create the JPEG?

Ah, sorry, I just realised that you are not using a Desktop version.

[Trevor.Dennis]

The example below looks like a lateral shift.

...but this one is a full on wobble.  It's like a corrupted 405 TV picture.

What are we looking at in the screen shots? Are they saved to drive images, or copies of the iPad screen?  I am wondering if this is a display glitch, and that the saved files would not show the issue.

I am not so sure how many of the forum regulars use Photoshop on the iPad.  I have an iPad Pro so I obviously have Photoshop on it, but I flat out hate it and never use it.  If that's the pattern of use for the forum regulars, then poster might be needing pot luck as to whether anyone who knows the platform will see their posts.