You will always receive five support notes in each Live (surrounded by triangles), randomly replacing any non-gimmick note in the note map. There are four Support Note types with different beneficial effects representing each Card type.

The type of the support notes you receive is randomly chosen from the three members in the SP skill centers of the other players in the room. That also means other players get your support notes, so you can set your SP skill centers up to influence which notes others can receive.

You can only get one support note from a player at most, because the game first decides which five players you get notes from, and then randomly picks the type from their SP centers.

The penlights you can see in the player list at the end of the Live Show tell you who you got support notes from (orange) and who received support notes based on your SP center (green).

Since the effect of Sp Support Notes is far more powerful than any of the other Support Notes, they are essential for getting a high placement in the Voltage Ranking. This results in Sp Lobbies: Voltage rankers get together with as many Sp type Cards in their center as they can, and join SBLs at the same time in hopes of getting into a lobby together, to have a higher chance of receiving Sp Support Notes.

On the JP server, these lobbies can often be found by following streamers on sites such as Mirrativ, where one ranker organises countdowns for an entire group of players to try to get as many into one lobby as possible. Streams like this do not exist for the GL server, but players still spontaneously come together for attempts at Sp Lobbies in Discord servers and the such.

The Item Support Note bug was a problem present from SBL 0, until it was fixed in SBL 14. When the bug was still active, you would sometimes encounter item drop notes (with the treasure chest icon) surrounded by the same triangle effect given to support notes - which is why they were nicknamed “Item Support Notes”.

They had none of the usual Support Note effects - they just added an extra reward drop, like a usual item drop note. As this Item Support Note would take the place of one of the five Support Notes usually received, the player would miss out on a big potential bonus. However, since this type of Support Note was not mentioned in any Help pages, and would not fit with the official description of the four Card types being aligned with the four Support Note types, it seemed like this was unintended behaviour.

It seems very likely this was a bug. Looking at network data, SBL Support Notes are mostly like regular Gimmick Notes, but they are defined in a different place than normal Note Gimmicks. The assumption is that when regular item drop notes are placed in the song, the server checks the usual Gimmick Notes location to make sure it's not slapping an item on a gimmick note. That way, when the game processes a hit on (an item note, it can skip the check for Gimmicks, and just add one to the extra drop counter.

However for SBL, the Support Note Gimmicks are not in the usual place, but some completely different one - which was not checked when distributing item notes. An overlap would result in these notes being surrounded by triangles (because they're meant to be supports), but wouldn’t proc the intended Support Note Gimmick because the item takes precedence. Assuming a 150 note song with 1 item note, there was a 3.33% chance to have an SBL live with a Support Note blocked by an item drop note.

This is unconfirmed - however, mails to Klab Support (since SBL 10) seemed to confirm the Item Support Note was not intended behaviour, since the reports of the note were immediately forwarded to staff. Item Support Notes kept appearing in SBLs, until SBL 14, where they disappeared.