Sometimes I will use two different stud finders to make absolutely sure I’m not drilling into anything I should not.

The stud finder I have is one that also shows electrical wiring, pipes for stack vents, bracing studs, etc.

Your wall could also be plaster and lathe, and that stuff can be a major pain in the ass.

Worst case, get another stud finder to confirm locations, and use a very small drill bit to check for wood under drywall.