Logical replication - ERROR: could not send data to WAL stream: cannot allocate memory for input buffer

Hello,

we are using logical replication for more than 2 years and today I've found
new not yet know error message from wal receiver. The replication was in
catchup mode (on publisher side some new tables were created and added to
publication, on subscriber side they were missing).

RDBMS version:PostgreSQL 11.4 (Ubuntu 11.4-1.pgdg18.04+1) on
x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 7.4.0-1ubuntu1~18.04.1) 7.4.0,
64-bit
OS: Ubuntu 18.04.2 LTS

RDBMS was installed from pgdg packages.

The error message:
2020-06-05 20:00:08 UTC 19753 5edaa378.4d29 2 0 540/1132087
[XX000]:ERROR: could not send data to WAL stream: cannot allocate memory
for input buffer
2020-06-05 20:00:08 UTC 867 5df8a0b4.363 28613 0 [00000]:LOG:
background worker "logical replication worker" (PID 19753) exited with
exit code 1

Repeated several times, finally it proceeded and switch into streaming
state. The OS has 64GB RAM, OS + database instance are using usually 20GB
rest is used as OS buffers. I've checked monitoring (sampled every 10
seconds) and no memory usage peak was visible, so unless it was a very
short memory usage peak, I'd not expect the system running out of memory.

Is there something I can do to diagnose and avoid this issue?

Thanks Ales