After upgrading to RHEL8 or above, 'awk' command's 'OFS' variable behaves slightly differently from the one in RHEL7.

Issue

Let's assume we have a file as below.

$ cat test.txt
a, b, c, d, e, f, g
h, i, j, k, l, m, n
o, p, q, r, s, t, u

In RHEL7, I got the following result with awk command.

RHEL7 ~]$ cat test.txt | awk -F, '{$1=$1; OFS="*"; print $0}'
a* b* c* d* e* f* g
h* i* j* k* l* m* n
o* p* q* r* s* t* u

However, in RHEL8 or above, I got a different result with the same command.

RHEL8 ~]$ cat test.txt | awk -F, '{$1=$1; OFS="*"; print $0}'
a  b  c  d  e  f  g
h* i* j* k* l* m* n
o* p* q* r* s* t* u

Why does this difference occur?