15 New Flags were added as part of patch 0.8.3.0/0.8.3.1.
Yukikaze – Azur Lane collaboration flag for the T8 premium ship Yukikaze
Montpellier – Azur Lane collaboration flag for the T8 premium ship Montelier
World of Warships Legends – Flag related to the warship legends videos, not sure how you acquire this flag, I will update this post when I find that info.
Privateers – Flag that is awarded to Privateers, a new program for supporters of the WoWS community without being content creators.
Metal Blood, Iris, Eastern Radiance, Eagle Union, Northern Union, Royal Navy, Sakura Empire, Vichya – Flags which are part of the Azur Lane collaboration.
Honor, Victory, Glory – Flags earned as part of the Friendly Victory competition event in-game, also known by players as the Honor and Glory competition.