I'm not familiar with the audio support you have but in our case, we have a dynamic live video stream coming from multiple sources so data is available only in memory.

Does GetRawTextureData have the same problem?

Yes, the internal pointer changes less frequently, but still replaced with a new one every few seconds or so.

Another suggestion, does it happen if you have a pool of Unity texture being used as a ring buffer? (update texture0 in frame0, update texture1 in frame 1).

Anyway I need to find time to analyze this.

Didn't try that, but using a ring buffer will force me to use a ring buffer of Noesis.TextureImageSource as well.
I guess they made this change to provide optimized support on multithreading rendering in some platforms.
Anyways, I'll stick with the blit workaround solution and will try to reach Unity support as well.

Please, let me now what Unity says about this if you contact them.