It isn't just Twilio. When I had T-Mobile, I was able to get 2FA SMS from about 1/3 of the companies that I use it with. Even financial companies like Vanguard and many others, never were let through with T-Mobile. I called T-Mobile and asked them to open it up completely. No improvement.

I switched my same phone with same phone number to another provider and I get all texts that I am hoping to get now and get literally no spam texts.