Thanks for the bug report. I reworked I2C this week and the tested the si7021 demo specifically, it should be ok.
Firmware main branch @ unknown (2024-10-12T17:20:50Z)
This seems a bit old, and the bus errors are no longer a thing because of how I wrote the new PIO program. Could you please try this one.
To be fair, I have not tested tsl2561 or the other demo because I can’t find the boards. I also did the I2C rework on v5 and haven’t tested on 6. I will do a complete test of everything before the end of the week.