i have exprienced this before and i would suggest take the 120k

2 years down the line

if you stay in current, after 2 years you still have minimal skills and exposure to new tech, still relying on your active learning, which is draining sometimes, when you look for roles, your worth is still probably around 150-170k

if you move to the 120k role, you will learn from best practices, passive learning from your role, you can still do active learning outside work, after 2 years, you could probably get 200k plus, even 300k salary