What I’ve found with most all of my early cover recordings was that although the bass line sounded fine when I posted to the B2B forum, many, many more people said that they couldn’t hear me play even though they saw me playing in the video.
What I realized was that the majority of B2B listeners will either use their computer attached to either an amp, headphones, or decent computer speakers with a subwoofer. As @terb mentioned, there are many other listeners who typically only use their phones which produce very little bass frequencies.
As such, I have since began to record with a little more prominence on the bass line so that the music appears to be a bit more bass balanced when listened through an iPhone. When listening using a more complex sound system, the capability to adjust the bass level is available, so the bass can be tuned down a bit as needed.
The majority of people who listen to my online bass covers or original songs will pretty much always use their iPhones - at least for a first listen…
Just my observations with what I’ve done. May be different for others though…
Keep on Thumpin’!