Apple and Google both provide support for offline speech-to-text using local models. Users can configure it to be fully offline.

The Murena Voice to Text service in /e/OS sends the user's audio to OpenAI which is hidden away in their terms of service:

https://community.e.foundation/t/voice-to-text-feature-using-open-ai/70509

Voice to Text feature using Open AI

Thank you a lot for your positive and supporting comments about our new /e/OS Voice-to-text! Regarding its implementation in /e/OS, I’d like to explain a few things to explain why we have chosen an OpenAI STT API to implement it and how it’s going to evolve in the future: What we have learned from our experimentations with STT models that run locally on the smartphone for speech recognition: they work quite poorly, they make a lot of mistakes in voice recognition they are not able to mix la...

/e/OS community
/e/OS is heavily marketed as private but in reality it has enormous privacy issues like this with their default apps and services. It's also heavily marketed as avoiding Google services but yet has privileged integration for Google services and connects to multiple by default.
/e/OS doesn't keep up with basic privacy or security patches for the OS or browser engine used not only for the default browser but also the WebView used by many apps including email clients and far more for rendering web-based content. For more info see https://discuss.grapheneos.org/d/24134-devices-lacking-standard-privacysecurity-patches-and-protections-arent-private.
Devices lacking standard privacy/security patches and protections aren't private - GrapheneOS Discussion Forum

GrapheneOS discussion forum

GrapheneOS Discussion Forum
/e/OS is not a threat to mass surveillance but rather significantly helps with it by making exploiting devices to extract data or take remote control over them far easier. They do not keep up with basic High and Critical severity patches. All devices sold by Murena are insecure.
Even on Pixels, /e/OS is extremely far behind on providing the current High and Critical severity privacy and security patches due to being so far behind on OS updates. They mislead users by setting a fake security patch level and changing the UI to mask what's happening.
Murena is a for-profit company and /e/OS is very clearly built and managed for the benefit of Murena. Despite this, /e/OS receives a huge amount of EU government funding. If you're an EU taxpayer, your money is being used to build this extraordinarily insecure and non-private OS.
@GrapheneOS false !
@s94 /e/OS is receiving millions of dollars in EU government funding. /e/OS is built and managed for the benefit of Murena, a for-profit company. /e/OS has the same leadership as Murena. What about this do you think is false?
@GrapheneOS Murena allows Ungoogled Android and open source to be democratized and accessible for everyone. It's maybe not perfect, but they have good intention and you can't disrespect them like that.

@s94 No, Murena is scamming people at a large scale for profit. They're pretending to provide a private OS which is in reality not at all private. We've explained how it lacks the most basic privacy and security. It even sends sensitive user data to OpenAI without informing users, which is far worse than how Apple and Google are handling speech-to-text from a privacy perspective.

Contrary to their marketing, it gives extensive privileged access to Google services and always connects to them.

@GrapheneOS OK so explain me how /e/OS is always connected to Google? (I am ready to change my ROM if you arrive to change my mind)
@s94 See the third party comparison at https://eylenburg.github.io/android_comparison.htm. It has a section covering the default Android Open Source Project connections. /e/OS leaves several still connecting to Google services. In addition to that, /e/OS has microG enabled by default and making additional Google connections beyond the ones in AOSP. /e/OS also adds an additional Google connection for carrier configuration not performed by AOSP which is covered at https://www.kuketz-blog.de/e-datenschutzfreundlich-bedeutet-nicht-zwangslaeufig-sicher-custom-roms-teil6/.
Comparison of Android-based Operating Systems

Comparison of Android-based Operating Systems

@GrapheneOS I bow to GrapheneOS