Should I stay at my current company or accept the new offer ?

I need some advice regarding a decision in my career. Lets begin with a small intro about me, I am a software developer based in Egypt with 3YOE as a dev (and a Civil Engineering background - total 5 years of work experience).

I currently work remotely for a Saudi company with Polish engineering team and few Egyptians. (worked there for 2 years), my current role is mostly Frontend.

Last year before renewing my contract, I expressed to my manager that I want to contribute as a fullstack developer because this is my long term career goal and that I can do that as I learn with myself (I am a self taught dev at the end of the day). He told me that we can do that, but that he couldn't promise.

The year has ended and my role was still purely FE. However, while renewing the contract for next year (2026), He revisited my previous demands, he told me that next year he can help me make the transition and participate in 1 or 2 features by the end of the year (framed this as an optimistic goal).

Overall, Working in my company is great, good working culture, low stress, low workload and totally remote with some flexibility for work hours.

Before renewing my contract, I was applying for other roles, and I had a technical interview for a full stack role at an Egyptian company. I was accepted and will have my HR interview next week.

The reviews for the new company are mixed, some say its a good work environment, others say the exact opposite. So work culture is uncertain. The company is a software house, (so they provide technical services for other companies/institutions/governments) and what most reviews agree on, is that it will help you learn and become a better developer as they have large projects.

I feel somehow overwhelmed, I am comfortable at my company, yet I feel I am not really advancing as I should. The new company seems to offer better growth path, but the work culture is uncertain. (Consider fairly similar compensations for both companies)

I would appreciate any advice or insight, how would you approach this if you were in my shoe

Thank you in advance.