Over the past 5 years, both main grading companies have gotten stricter on vintage grading. PSA for edge and corner issues is even stricter, making colored bordered cards like 1971 and 1975 Topps even more difficult to score high grades on. SGC used to forgive centering, but has really tightened up on it recently.
But truthfully, PSA is always a 1-2 grade crapshoot. If you are expecting accuracy from PSA, you're doing it wrong.
Plus, if you've been out of the hobby 30 years, you should really read the PSA/SGC trimming scandal threads here and on blowout. Start with this one:
https://www.blowoutforums.com/showthread.php?t=1298835
https://www.blowoutforums.com/showthread.php?t=1289859
You could be still reading months from now, based on how many fraudsters there are and how incompetent the grading services are. And for some real fun, the T206 Auto scandal thread is also a good one to show their incompetence.