Problem after iPadOS 15.4 update

Some Apps may require update to be fully compatible with the iOS/iPadOS update. This is true of any Operating System, not just Apple.

App Developers have access to beta versions of software updates prior to release - so as to ensure that their Apps remain functional with system calls and APIs upon which the App may depend. Not all Developers update their software in a timely manner - in particular those where the derived revenue from sales of the App do not justify the ongoing costs of software development. Older Apps may be entirely abandoned - and may cease to be usable.

You would be well advised to contact the App Developer for support - and information concerning future update:

How to contact an app developer - Apple Support

Having looked at the App Store, assuming that this is indeed the App in question, I note that an update was released about 9 hours ago:

https://apps.apple.com/gb/app/nowserving-by-seriousmd/id1490833154

The linked App may not be available in some regions - or may require a private link to install. As such, other than advice already provided vis making contact with the Developer, it’s difficult to offer additional comment.

I also have had issues with the last two updates which came within a short time of each other in March of 2022. I’m having trouble with some of my games and a jigsaw puzzle app. They keep stalling or stop for awhile. It’s very aggravating. I used to completely shut down the iPad for a minute or two to fix any problems, but even that doesn’t work for very long now. I also hate other things it does now too, like the “icons” that appear and then disappear at the bottom of a screen. They seem to interfere with the function of at least one website.

I also had problem with Amazon & Eufy apps. But the worst is that now the iPad is stuck. None of the Apple instructions to reboot it works. And now I am waiting the battery drains completely to, hopefully start it up. *****.

pdrpol, the day before you wrote, I let my battery drain completely before charging it. So far, it appears to be a little better. I hope you found the same. The real test will be this weekend. I'm always in a word tournament on weekends, and that's when it acts up more than ever with the app. (But the update still affected others.) Time will tell. Good luck.

That’s why they tell you to not update within 2 weeks… anyway get more help here: Official Apple Support

After update 15.4, now I can’t turn off iPad 6 mini, some apps will not update. Is there a fix from apple coming?