I’m a IT-Specialist for application development

Appeal to authority.

Session is indeed a good competitor

Unfounded claim.

thought they had some flaws

Flaws they introduced by removing PFS (Perfect Forward Secrecy) and Cryptographic Deniability, just to name two big ones, which they got free from Signal. For anyone not aware, they removed these security features because it made development more difficult for them, not because it was in the interest of their users.

upcoming V2 protocol would’ve fixed

Has yet to be seen, although if they bring back PFS, they will have at least reached Signal's level of privacy/security from over a decade ago

Edit:
Additional, more technical details on why you shouldn't use Sessions: https://soatok.blog/2025/01/14/dont-use-session-signal-fork/

I believe your technical understanding is flawed

Its interesting that you assumed that my objections stemmed from technical problems. Why is that?

Its not, its from usability and trust and poor decisions.

The fact that they're going to run out of money and the entire platform will just cease to exist is itself my primary objection, much the same as Signal and other centralized services.

The fact that it even costs so much to run is another.

And thirdly, their involvement in crypto shenanigans is an instant dealbreaker.