What does a red flag next to a weapon mean?
On the weapon select screen, I noticed there was a red flag next to my Splattershot. All of my other weapons had a gray flag. What does the red flag next to my Splattershot mean?
That's a mechaninc also present in Splatoon 2, and as https://www.reddit.com/r/splatoon/comments/xcmv5d/splatoon_3_faq_answers_to_commonly_asked/ and the official wikia too, it's the Turf War freshness:
(Not to be confused with Weapon freshness!)
Indicated by stars
Each rating has a specific flag color that is displayed beside a weapon's name in the weapon select. The flag's color is representative of that weapon's highest Freshness rating, not its current rating.
Turf War freshness (flag) is shown in an icon on the right when selecting Turf War from the lobby menu. It correlates to how many matches you've won or lost with your equipped weapon. Winning will increase the bar, and losing will decrease it. As the meter increases, your weapon will be marked with a little colored flag next to its name in your equipment screen, corresponding to how much Turf War freshness you've attained with it.
This is how https://splatoonwiki.org/wiki/Freshness chart works:
Title Score to Reach Score Penalty on Loss Bonus on Reaching Flag Color 0 -0.5 N/A Grey 5 -1 3000p Green 10 -1.5 4500p Orange 15 -2 6000p Silver SUPERFRESH! 20 -2.5 No bonus White 50 -3 No bonus Gold