Redis LUA script eval flags: user_script:1: unexpected symbol near '#' - redis

Question

I have a LUA script that fetches a SET data-type and iterates through it's members. This set contains a list of other SET data-types (which ill call the secondary sets for clarity).
For context, the secondary SETs are lists of cache keys, majority of cache keys within these secondary sets reference cache items that no longer exist, these lists grow exponentially in size so my goal is to check each of these cache keys; within each secondary set to see if they have expired and if so, remove them from the secondary set, thus reducing the size and conserving memory.
local pending = redis.call('SMEMBERS', KEYS[1])
for i, key in ipairs(pending) do
redis.call('SREM', KEYS[1], key)
local keys = redis.call('SMEMBERS', key)
local expired = {}
for i, taggedKey in ipairs(keys) do
local ttl = redis.call('ttl', taggedKey)
if ttl == -2 then
table.insert(expired, taggedKey)
end
end
if #expired > 0 then
redis.call('SREM', key, unpack(expired))
end
end
The script above works perfectly, until one of the secondary set keys contain a different hash-slot, the error I receive is:
Lua script attempted to access keys of different hash slots
Looking through the docs, I noticed that Redis allows this to be bypassed with an EVAL flag allow-cross-slot-keys, so following that example I updated my script to the following
#!lua flags=allow-cross-slot-keys
local pending = redis.call('SMEMBERS', KEYS[1])
for i, key in ipairs(pending) do
redis.call('SREM', KEYS[1], key)
local keys = redis.call('SMEMBERS', key)
local expired = {}
for i, taggedKey in ipairs(keys) do
local ttl = redis.call('ttl', taggedKey)
if ttl == -2 then
table.insert(expired, taggedKey)
end
end
if #expired > 0 then
redis.call('SREM', key, unpack(expired))
end
end
I'm now strangely left with the error:
"ERR Error compiling script (new function): user_script:1: unexpected symbol near '#'"
Any help appreciated, have reached out to the pocket burner that is Redis Enterprise but still awaiting a response.
For awareness, this is to clean up the shoddy Laravel Redis implementation where they create these sets to manage tagged cache but never clean them up, over time they amount to gigabytes in wasted space, and if your eviction policy requires allkeys-lfu then all your cache will be pushed out in favour of this messy garbage Laravel leaves behind, leaving you with a worthless caching system or thousands of dollars out of pocket to increase RAM.
Edit: It would seem we're on Redis 6.2 and those flags are Redis 7+ unlikely there is a solution suitable for 6.2 but if there is please let me know.