Debug messages disappear

I have 2 flows:

flow 1 spits a large number of messages.
flow 2 not so much

In editor, I select "current flow"
I select flow 2, spits 2 messages, waiting 5 seconds, they disappear.

Is the "current flow" only a visual filter ? I can imagine that node-red can not keep all messages in the debug tab.
It is not an issue as I need to reduce the message flow, but was just wondering.

Correct. The editor is still receiving all the messages, it is just displaying those that match the filter you have selected.

How many messages are being kept ?

All of the messages are added to the debug sidebar. The filter then decides which are shown and which are hidden. Once the maximum number of messages have been received, the oldest one is removed from the sidebar regardless of the filter.

Hello

I noticed a wired behavior on my Node-Red editor today, which is similar to the one described above.
I have a 16 flows running, each flow receive a message every second from the MQTT.
When I left one of the debug nodes enabled on one of the flows, messages started disappearing from the debug window in the other flow when filter was enabled.
Summary: Flow 1 receive msg. every second then on Flow 2 with filter "current flow" applied messages from debug window start to disappear .
Video

@krzydec please read my previous comment. You have described exactly what I said the existing behaviour is.