But you have continued here to argue on the absence of evidence. You aren't bring forward any positive evidence.
Explicitly.
There is no evidence of whether the character is wearing gloves other than the broad fact of wearing a set of undefined traveler's clothes.
Just because nothing contradicts the possibility that gloves are part of the clothing does not mean that there are gloves.
Correct, and vice versa.
Just because nothing contradicts the possibility that gloves are not a part of the clothing set does not mean that there are no gloves.
You can't retcon on the basis of the absence of evidence. This is like VAR in soccer. If you want to overturn the referee's call on the field you have to present definitive evidence that the call is wrong. The GM and not the player is wearing the referee hat. The GM's call and not the players call is the one that has authority. The GM is the referee. Everyone that is sitting at the table agreed to that implicitly and explicitly. Arguing with the referee is just poor sportsmanship.
This is the part you are presenting as fact and I am disagreeing with.
The DM took an undeclared player detail and declared it.
Different groups can have different boundaries between DM and player roles. Declaring undeclared details about a PC can be but is not normally the DM's job.
Making up PC choices and details is not a referee type ruling, it is an editorial one.
Which the DM has every right to do. The DM has every right to decide by fiat whatever is vague or debatable or unstated or unknown.
Another view is the players determine the details of their characters and the DM determines things about the world the players interact with.
And if I'm the other player sitting at this table while you are arguing with the GM, I'm really wishing that in addition to filing a review of the GM with the convention, I can file a review of the player and ask that they never again be allowed to waste my time. And if you are a friend pulling that stunt, I'm like, "Just roll the dice and get on with the game.", the same way I feel when parents are yelling at the referee in a soccer game about every single call as if they could do a better job or something. And 90% of the time, the parents are just flat out wrong because the laws of the game aren't that the player who went down harder was the one that committed the foul, which almost every parent seems to think.
My experience is sometimes players will be fine with DMs crossing over into dictating stuff for a player and sometimes they will not. When a player says something reasonable about their character most experiences I have had have been other players supporting them and not chastising them for taking any time to argue.
If for instance the player had a character portrait with gloves which nobody else had seen, I think everybody would be on board with it even though the DM had decided differently by fiat based on the unknown.
I think it would be the same for a difference of opinion on unstated character details, generally people expect the PC to be the one who can determine those and a DM who crosses over one should generally respect the PC's views of them.
The time it has crossed over into fellow PC disapproval in my experience has been after the DM hearing the player's argument and the player then not accepting "I'm ruling this way for now so we can keep going." and the player continuing to argue the point and delaying the action further. Not for initially speaking up about a factor that goes in the player's favor.