No HR
Management is completely clueless, do not know what the employees job requirements are
No room for growth, for some reason management almost exclusively hires managers externally
Due to this, almost all direct managers do not know how to do the job for at least 4-5 months, which makes them essentially middle men for upper management.
Bad pay
History of punishing employees with extended probationary periods/performance plans/refusing pay rises due to personal vendettas
Unstable growth model, overworking employees who need to train new hires at an untenable rate while dealing with a greatly increased workload, leading to more mistakes with new hires.
This is for Octopus Energy Services in particular, as I do not have firsthand experience at Octopus Energy.