FWIW, I had a very positive experience getting a refund from TAP.
I needed to cancel one flight last summer on TAP, from the Azores to Lisbon (I ended up booking a different flight later). Based on my reading of the refund rules in place at the time, I thought I should qualify for a full refund if I cancelled, but was concerned about all the complaints I saw online about dealing with TAP. This was in May or June -- I don't recall exactly, but at the time there was a huge COVID spike in Portugal, so I was expecting the worst (LOTS of UK residents were cancelling flights around then). To my surprise, I called TAP and got right through - phone was answered quickly by (what sounded like) a young woman, I could hear her dog barking, she was clearly working from home. I had all my info and gave it to her. She quickly confirmed that yes, I would be eligible for credit or a refund, whichever I preferred. I asked for the refund, she said no problem, the funds will be credited back to your credit card within 90 days (I was prepared for that, I had read the terms and they did say refunds would be within 90 days, not instant). I said OK. We chatted for a few minutes, she said she was indeed working from home (I could hear the dog and birds in the background), in a suburb of Lisbon, we exchanged pleasantries, wishes for COVID to end soon, etc. That was it, easy, quick and pleasant. Just short of 90 days later, the funds were credited back to my credit card, as promised.
So, while I'm sure there are plenty of posts online from people who are mad at TAP for something, my experience was just fine (and one would be hard-pressed to find any airline that doesn't have bad reviews online...). I booked and flew several legs on TAP during that trip last August and September, and they were perfectly fine. YMMV, but I'd have no concerns whatsoever about booking and flying with them in the future.