It takes guts to say “this 1 month feature would be done in a couple days by a competent competitor using modern technology and techniques”, and the legendary “I reimplemented it in <framework> over the weekend” is often not well received.

But - sometimes drastic measures and hurt feeling are needed to break out of a bad attractor. Just be sure you’re OK with leaving the company/org if your play does not succeed.

And know that as the OP describes, it’s a lot about politics. If you convince management that there is a problem, you have severely undermined your technical leadership. Game out how that could unfold! In a small company maybe you can be the new TL, but probably don’t try to unseat the founder/CTO. In a big company you are unlikely to overturn many layers above you of technical leadership.