According to Paul D Thacker in this article published in the BMJ, a whistleblower working for a subcontractor in Texas (Ventavia Research Group) reported a number of problems, and was then immediately fired after informing the FDA.
She then listed a dozen concerns she had witnessed, including:
Participants placed in a hallway after injection and not being monitored by clinical staff
Lack of timely follow-up of patients who experienced adverse events
Protocol deviations not being reported
Vaccines not being stored at proper temperatures
Mislabelled laboratory specimens, and
Targeting of Ventavia staff for reporting these types of problems.
Are these serious problems for a clinical trial site, and do they mean that the results of the Pfizer clinical trial as a whole are questionable?