QFX5120-48Y and QFX5120-32C series switch, you may observe below error when applying firewall filter.

Oct 23 09:52:46 Switch fpc0 ERROR (dfw): Max Counter Reached 8193
Oct 23 09:52:46 Switch fpc0 ERROR (dfw): Max Counter Reached 8193

If you observe this message with available TCAM space, it may be a software bug. This KB describes this and share the PR information.

On QFX5120-48Y and QFX5120-32C series switch, firewall filters counters are not getting scaled with error "Max Counter Reached 8193".
At that time, there are some TCAM available entries.

user@Switch# run show pfe filter hw summary

Slot 0

Unit:0:

Group                    Group-ID       Pipe      Allocated      Used      Free
-------------------------------------------------------------------------------
> Ingress filter groups:
  iRACL group            33             0         2304           2050      254
  iRACL group            34             1         2304           2050      254   <<<===== here
> Egress filter groups:
  eRACL group            54             0         1024           1024      0
  eRACL group            55             1         1024           1024      0   <<<===== here
  eRACL IPV6 group       64             0         1024           1024      0
  eRACL IPV6 group       65             1         1024           1024      0   <<<===== here

Above output mentions 254 free entries remained in iRACL, but not able to add firewall filter on iRACL when having a "count" action.
The issue is not seen with QFX5120-48T though loading the same configuration.

This is a software bug reported by PR1844634.

https://prsearch.juniper.net/#!/search?page=prcontent&id=PR1844634

In case of QFX5120-48Y, it counts twice for the number of 'count' action compared to QFX5120-48T. And it's system limit is 8193 and hence the error is seen.
The software fix has been provided to cover such scenario so all of TCAM space will be used with 'count' action.