it isn't just two appearances of a blonde woman.
There is the small fact of them following each other on IG. He is the only straight male celebrity she has ever followed on IG (apart from Kurtis till 2022). Bryson, for his part, does not follow any other model or non-golf female celebrity (apart from a few conservative politicians). This alone tells us they are very into each other. Personally I wouldn't need the sightings to conclude they are more than just friends.
We also have her posting, on the day that she was sighted at the LIV final, a set of her excitedly stripping in front of screen showing that very championship. This was the only time her OF posts have ever referenced a real world event, let alone as it happened.
A week later she posts a story from a golfing retreat in the UK, a country she has never before visited or posted anything else from.
Finally, there is more than blonde hair to link mikayla to the woman in the picture. Hairstyle, height, bust size and shape, face shape and bone structure , mouth and even arm shape and posture are similar to Mikayla. Whereas none of his three previous girfriends fits the characteristics of the woman in the clip. Sophia Bertolami's face from some angles looks similar but her face is clearly more elongated. Also her figure is slighter than the woman in the clip.
All of this taken together leaves little basis for reasonable doubt, the more so as there is nothing in the least surprising about them dating.