I hate when senior developers who sit in the same project for centuries are closed for any suggestion and do no challenge their own work and environment.

Whyyyyyyyyy

I feel your pain!
I've found that finding out what sparks their engagement with the code and trying to build a rapport builds trust and eventual respect by veteran Devs.
That and asking lots of questions about what they see is wrong about the legacy and solutions they've come up with but have failed - as you and other devs are still trying to fix something.
Pair programming and general catch-ups are a fab, organic way to do this. Brothers/sisters in arms and all that ⚔️🍻😝

They got burned.

@fzammetti my rant has nothing to do with seniority itself. It's more about being senior (which, in this case, includes the ability to make conscious decisions and not focusing only on short time execution perspective), AND being in the same project for years, AND being unable to take a look on your existing work, then, even internally, identifying own mistakes and suggesting better solutions. The team tries to make some improvements to existing system's design, but cannot do much about it due to people that say just "no" and their judgement is grounded in years they have spent working on this product rather than actual explanation why this or that won't do better job than existing design.