For what it's worth, since the Russian space littering event, I am getting almost
daily Close approach alerts on PCSAT (is a high orbit, originally 800 km high).
Alert miss-distances seem to be on the order of 200 to 500 meters
Example Alert below at end..

Another day in space (after 20 years for PCSAT
Live downlink (W3ADO-1):
One minute serial nos (T#xxx), suggest a wake from1 to 8 minutes per orbit.
PCSAT is unique in that is has no CPU or Operating system.  It is just two off-
the-shelf KPC9612 TNC's (chips in sockets, etc) and uses their built-in sysop 
features for telemetry, command and control.
Follow-on APRS satellites:

---------- Forwarded message ---------
Date: Tue, Nov 30, 2021 at 2:40 PM
Subject: PCSAT Close Approach Notification

The United States 18th Space Control Squadron has identified a close approach between PCSAT (SCC #26931) and SCC #30230

Time of Closest Approach: 2021-335T02:20:51(UTC)
Probability of Collision (Pc): 0.0003769653
Overall miss distance: 338.0m

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