The very slight "cratering" you see around the firing pin indent is normal for some primers.
Even flattening of primers can be OK, depending on the primer.
Commercial primers, intended for handloaders such as ourselves and the other knowledgeable people who answered you, tend to be softer.
Many of the primers available recently have been made to military specs, and they tend to be harder. When you get primer cratering, combined with extreme flattening, then it's a pretty good indication of high pressure.
The best way to check for pressure signs is to measure the diameters of the case, just in front of the extractor groove. If you're getting expansion of more than a few thousandths, you're getting high pressure.
Primer flow should only be used as an early indicator, but because of differing hardness, and thickness, it can be misleading.
Good on you for asking for verification.