20-25dB over the noise is good. How strong is the upper beacon?
I see different levels when i compare gqrx and sdr-console, both getting their data from the same sdr dongle on a server running rtl_tcp. In gqrx, the lower beacon is 30-35dB over noise (when tx-ing the steady carrier) , the upper beacon 27dB. In sdr-console, the lower beacon is only 15dB , the upper beacon 25dB over noise.
Maybe it depends on the settings. Experiment with LNA-Gain etc. Compare weak signals with web-sdrs to evaluate your setup. I can read many weak signals better on my own setup than on https://eshail.batc.org.uk/nb/ .