Question : What does it mean "Specific Weapon on rotation for a limited time" ?

[Sushimo]

I purchased Season 1. This is the first time that I buy a season. There is one weapon that I like but it says "Specific Weapon on rotation for a limited time". Does this means that once the Season is done that this weapon will be gone and inaccessible to me anymore ?

[Torean]

You will retain access after the season is over. Other than challenges though, Im not sure what the purpose is for.

[Pure & Rustic]

Why can't you tell what weapon this is all about????

I can't see any weapon in BP that say it is "Weapon on rotation for a Limitid time".

I have unlocked all sectors up to 8 and then 12-13-14 and 16.

Noone of the one I don't have unlocked say this.
If it is the event weapon, the LMG DG58-LSW - it is an event weapon that end in about 12 hours. That weapon will be gone and maybe come back in a packet you have to buy.