iPhone XS Max Battery case hiccup

[tl01]

My Apple Max battery case is behaving oddly today. My phone has been in the case all day and the case has had charge all day...my case is currently 23 percent charged and my phone is decreasing while it says it is being charged. I tried restarting and the same thing is happening. Anyone else have this issue. Somehow the case and phone are both draining.

 

[Bobby dazzler]

Evening,

Without all info I’d try the following:

Disengage battery case
Charge case
Charge iPhone and hard reset it
Re-engage case
See what happens.

My battery case has been fine and flawless for what seems like ages.
Is the charging port clean or does it have pocket fluff in it?
Hope you sort it!