I've never taken one, and don't plan to, either, based on stories like yours.
The man and his wife living next door to me went to get their flu shot in late summer 2020, and within days both were diagnosed with Covid. They believed they just picked it up from someone at the clinic. I just listened from across the yard and didn't share with them my first thought, which was wonder what was in those shots.
Likely they didn’t have covid. From what I understand the test can’t distinguish between the flu and covid. Probably the normal immune reaction to the flu vaccine caused the covid positive test result.
Other very reasonable possibility is that they had nothing. The covid test besides, being unable to distinguish between the flu and covid, has a 50% or better false positive rate.