I believe LUMIN does app software work for Esoteric. Wklie is LUMIN Firmware Lead and is very responsive to these type questions for LUMIN as well as app for Esoteric. I do not recall seeing him active here, but he is active on Audioshark and Audiophile Style forums. Audioshark has forum there specifically for Esoteric as well as LUMIN. It was not clear to me what source you are using to stream. I have a LUMIN X1 and use the LUMIN app as well as Roon and Qobuz. If you are using Roon, you will want to check if you have Sample Rate conversion enabled, and if so, what those settings are. On the LUMIN app, which could be very similar to the Esoteric app, there is a setting for Audio Analog Re-Sampling. I have that switched off, but if turned on to Custom, I still did not see MP3 resolutions. Suggest if you post this issue for Wklie, you indicate streaming source, your firmware and app versions, and the equipment in the Esoteric input path.
Best of luck in resolving.