Player 2 has random button presses on Famicom AV or Twin Famicom with Super Mario Bros. 3

[DoomyDoomer]

BlueRetro firmware version

1.9.1

BlueRetro firmware specification

HW1

BlueRetro firmware variant

System specific

BlueRetro hardware type

External adapter dongle (1 port only)

Manufacturer

Humble Bazooka

System used

Nintendo Famicom NES

Bluetooth controller brand & name

8BitDo NES DIY, 8BitDo Neo Geo, Sony DualSense, Xbox Series

What is problem? (only list ONE problem per report)

When using BlueRetro on a Famicom AV or Twin Famicom, Super Mario Bros. 3 has random button inputs on Player 2. This happens even if no bluetooth controller is connected to P2. I've tested the Japanese and US versions of Mario 3 and they both share the issue. The original Famicom doesn't have this same issue.

What did you expect to happen?

No rogue button presses.

Attach files like logs or Bluetooth traces here

No response

[darthcloud]

Just adding a note, that we tried a lot of things but somehow we can't find what the magic sauce is to get AVFC to not have random inputs.

My BlueRetroDev board do not exhibit that issue, but anything else does.