If fixed supply can be infinitely inflated (when it comes to price) and thus creating a bubble that can burst, it is not being different from supply that is not fixed.
In what case can the supply of bitcoin increase because it is a limited number with a size that never changes. What kind of supply are you talking about?
Bitcoin never increases in terms of supply but rather its price continues to find support. If what you mean is how the price continues to rise, it is a sign that there is a role of support provided or that the supply and demand process always occurs in the same direction.
Real support is not what is visible, but sometimes we have another side of how prices can affect the rise or fall in the market.
Bitcoin does not easily lose value like Tether because it always runs according to existing cycles.