After FIS acquired Worldpay, they reduced all employees salary, notifying everyone they were legally allowed to do so. Even being legal to do so, this demonstrated that FIS was not a company that values its employees. This and numerous redundancies resulted in Worldpay becoming a shell of what it once was in the UK.
The Security organisation was dysfunctional and it seemed to be solely compliance driven without any knowledge or understanding of newer technologies used by Worldpay. This led to a lot of attempts to use solutions which did not work with the different technologies they acquired. Unfortunately, this was driven by cost cutting and FIS employees preference in tooling, therefore not using the solution that was right for the job. For a company that prides itself on being a "FinTech" this approach seemed counterintuitive.
Work life balance was also difficult as US colleagues often disregarded time differences, scheduling calls late into the evening.