Star Trek: Discovery season 4 will debut new color-coded uniforms that properly synch up with Star Trek tradition. Paramount+'s flagship Star Trek series charted the franchise's new future when the USS Discovery jumped into the 32nd century in season 3. Michael Burnham (Sonequa Martin-Green) learned the cause of The Burn and saved the universe in Star Trek: Discovery season 3, which ended with Burnham becoming the new Captain of the titular starship and the crew donning Starfleet's 32nd century-era grey uniforms.
Since Star Trek: The Original Series, color coding (because the 1960s TV series took advantage of new color television technology) was a fixture of Starfleet uniforms. As a starship Captain, James T. Kirk (William Shatner) donned a gold uniform to denote Command. Mr. Spock (Leonard Nimoy), as Science Officer, and Dr. Leonard McCoy (DeForrest Kelley) wore blue, which was the color of Sciences and Medicine. Montgomery Scott (James Doohan) wore red as Chief Engineer, as did the various members of the starship's Security (who often died and were nicknamed Red Shirts). The Star Trek TOS movies broke this tradition; Star Trek: The Motion Picture introduced monochrome grey uniforms and then Star Trek II: The Wrath of Khan changed to naval-themed crimson uniforms that the TOS cast wore for the rest of their films. When Star Trek: The Next Generation premiered, it brought back color-coded uniforms but swapped red as the color of Command and gold became the color of Engineering. Star Trek: Deep Space Nine and Star Trek: Voyager maintained this color scheme with their jumpsuit uniforms. Star Trek: Enterprise debuted blue jumpsuit uniforms but kept gold, blue, and red stripes to denote each officer's specialty.
Star Trek: Discovery season 4's trailer revealed that the 32nd-century Starfleet changes uniform styles again and go back to proper color-coding. Captain Michael Burnham and the crew of the USS Discovery have traded their grey uniforms, which had a color stripe denoting their division, as well as their prior blue uniforms, which they lost at the end of season 3. The new Discovery season 4 uniforms are now red for Command, Gold for Operations and Security, and Blue for Sciences, similar to the 24th-century TNG-era color scheme. Additionally, there's now a dark stripe down the right side of each uniform's torso.
One significant break in tradition is the uniforms worn by Discovery's Medical team. Dr. Hugh Culber (Wilson Cruz) and his staff wear white uniforms with a blue stripe to denote the Medicines division. Star Trek: Discovery's doctors have deviated from the Star Trek tradition of medical staff wearing Science blue since season 1. Culber has always worn a white uniform, and that is continuing in the 32nd century (despite white being an odd color choice for a profession that deals with blood of different colors, depending on the patient being human, Vulcan, or another alien species).
Like Star Trek: Enterprise, Star Trek: Discovery's crew wore blue Starfleet uniforms from seasons 1 to 3. In fact, Discovery's blue uniforms were retconned to be standard in the show's original timeframe of 2255. The traditional color-coded TOS-era uniforms were then introduced in Star Trek: Discovery season 2 when Captain Christopher Pike (Anson Mount) and the USS Enterprise joined the show. However, Pike changed from his gold uniform to Star Trek: Discovery's blue suit for the duration when he left the Enterprise to take command of the Discovery. The 32nd century has now come full-circle in Star Trek: Discovery season 4 so that Captain Burnham now sports the same colors as Captains Picard (Patrick Stewart), Sisko (Avery Brooks), and Janeway (Kate Mulgrew).