Are these all on your home screen?
If so, you need to long press on each icon and move to trash or choose delete.
Then go into your app drawer and long press the app icons you want to the home screen again.
Problem solved

 

This happens with all of your user (not preinstalled) apps?
Or only just a few?

 

You may have to do a factory reset

 

your phone came out in 2015. most phones have an average lifespan of 3-4 years.....so you are way past that point. i'm not surprised on what is going on with your phone. as they get older things start to not work right. mainly because your os is now outdated and most apps do not support the older os so things will start to not work right over time.

you might want to start to at least look into getting a new phone......just saying.

on that note why are you constanly restarting your phone? how often do you do this? turning your phone on and off constantly is not good for your phone's processor.

 

I have the same issue on my G4. Every time the phone gets restarted, some of the apps and settings get deleted. (incl. Play Store and several other apps) This problem started to appear 1-2 weeks ago on my phone, and, interestingly, this topic is also posted just a few days ago. There might be something has happened to G4 phones during these weeks?

 

like i asked the op, how often do you restart your phone? i rarely restart my phone. it does need to from time to time, but is should not be done frequently.....especially on an older device. constantly rebooting the phone just wears out the processor.

 

I have not restarted it myself by now, except for very rare cases. The only restart it sees is when the battery/charge runs out of power. Yeah I know, this is an old model and such things are quite normal. The interesting part for me is the coincidence of these two issues at the almost same time. Looks like I'll have to spend extra effort not to let it turn off until replacing by a new one

 

I also have a G4 and have the same issue. Starting sometime in the last week or two when I reboot my phone, random apps, though it does seem to be the same selection of apps are uninstalled.