I hope this post helps someone out there dealing with this issue.  Less than 24 hrs after getting my S25+ Samsung Galaxy, my screen would flicker, then the phone would turn on and off several times, and then go into safe mode.  I took it back to the T-Mobile store, and they couldn't figure it out but did a soft reset, and it appeared to fix the problem.  Well, about a week later, it did it again, and back to the store I went.  I asked if it could be an issue with an app, and they said --"NO, Galaxy has safeguards on these new phones...bla bla bla."  They said it must be a faulty phone and gave me a new one.  Everything worked great for about a week, and then the same issue--screen flicker, phone would restart several times, then finally--Safe Mode.  Weirdly, all of my 3rd party apps were all still there and accessible in safe mode--which isn't supposed to happen.

So, to make a very long and frustrating story short, it was indeed an app that was causing this issue!  I had an app from my old galaxy that was once free but now costs money that transferred to my new phone, and that is what was causing all my problems.  Once I removed that app, the phone worked fine.  It was a process--Factory reset--installing a couple of apps at a time, and figuring out which one was the issue.  On a positive note, I did have a reason to delete all the worthless apps that I had downloaded over the years that I didn't need and just took up space.