Customer suspects a memory problem on the Juniper SRX 1500 cluster, for information we updated the software version yesterday between 10:00 and 13:30, today at 09:57 we lost customer service.

After upgrade from 21.4R3-S3 to 21.4R3-S7, customer faced issue related to traffic through the device.
In problem-state RSI we can see:
  close reason - memory shortage fail close                      30182320
which is confirmed by customer's session logs "memory shortage in fail close mode":

This is a memory leak introduced by a fix introduced in another PR PR1770967.
This Issue affects the following junos releases: 21.2R3-S8, 21.4R3-S7/8, 22.2R3-S3/4, 22.4R3-S2/3, 23.2, 23.2R2-S1 and 24.2R1.
All other junos releases are not affected by this issue.

This issue has been identified and fixed by PR below:
https://prsearch.juniper.net/problemreport/PR1826377