One change per decade is not a change.
More than once per decade: C11, C17, C23
I guess you can say C17 is a change if you want to be pedantic except it didn't actually introduce any new features; it just corrected some defects found in C11.
So we have C89, C99, C11, and C2X (C23?) as the only revisions introducing new stuff...
And you will be forever left writing insecure memory unsafe code.