Tackling Toxic Work Culture

I work in an early stage startup. The startup expects you to work any number of hours which seem suitable for the job. Saturdays are official. The product manager of the team doesn't bring the requirements clearly and just asks engineers to build what the client wants. The engineers do all the competitive market research and build features. Additionally, boot licking of seniors and leaders is ingrained in his nature. All he does is ask for updates on the tasks and if something breaks which may not be a bug just creates a bug ticket of it and then asks for updates on them without verifying if it is reproducible. This creates a lot of tickets and at times a single engineer dealing with 20+ tickets. Additionally, he pings on Sundays for random issues and updates. He also posts random warning or error logs from applications and asks engineers to check them without knowing the context and if there is an issue the client is facing. The CTO, the VP and the director doesn't push back this behaviour and adhoc requests on engineers from PMs. How to work in such an environment? Concerned since have only spent about 4 months in the job.

Please give practical tips and advices.