400 Pro app issues

Just swapped from V3 to 400 pro as I actually couldn't be arsed with the fold but... This new phone of mine won't open apps (50%), is extremely slow to open apps (25%) or the rest are just fine. I've uninstalled them, reinstalled them, shut them all down, done a force restart and finally last night after having enough of this crap I wiped the whole phone and did a factory reset. I had read on here copying one phone to another (which I did at first) can make some apps buggy so today I have reinstalled a handful of apps from Google Play to find.... some still do it! Have I got a busted phone? Does having an Honor pad in some way affect these apps (because this seemed to start when my Honor Pad arrived and I loaded that). I have a phone that basically is now just a phone 😖