Could it be that I have too many lists enabled

yes,

Could also be that the default "Firewall Maximum Table Entries" setting is too low.
You will find this entry here: System -> Advanced -> Firewall & Nat

A lot of people select far too many lists - generally not needed.
the setting should generally be twice the value actually required. When the lists are processed to the firewall, the entire new set is created, then swapped into place.

Look for this log entry in the pfbockerng.log. That will give you some guidance to the setting best suited for your case. In my case it is deliberately higher than the 2x referenced.

pfSense Table Stats
-------------------
table-entries hard limit   600000
Table Usage Count         135911

Just above that in the log you should see the summary, like this:

Alias table IP Counts
-----------------------------
  134581 total
  107656 /var/db/aliastables/pfB_???_v4.txt
   11244 /var/db/aliastables/pfB_???_v4.txt
    6505 /var/db/aliastables/pfB_???_v4.txt
    6208 /var/db/aliastables/pfB_???_v4.txt
    2608 /var/db/aliastables/pfB_???_v4.txt
     228 /var/db/aliastables/pfB_???_v4.txt
     132 /var/db/aliastables/pfB_???_v4.txt

the ??? will be the name of the list

Could it be that I have too many lists enabled in pfBlocker and just need to reduce my list? I will try to cat it and see what I get as well.

"/var/db/aliastables/pfB_PRI5_v4.txt"

SSH, or Console into your pfSense (do not use Diagnostics > Command Prompt ! ) and have a look at that file.

If your fast enough :

cat /var/db/aliastables/pfB_PRI5_v4.txt

wc -l /var/db/aliastables/pfB_PRI5_v4.txt

will count the number of lines = the number of networks / DNSBL
The error was : all this can't be read into 'pf', the firewall.
Solution : reduce your ... whatever you've selected.