I have a 2019 Giant Contend 3 road bike and I have been having an issue with this bike on and off for the past month. The issue is that when I start pedaling the bike it vibrates. The vibration seems to be coming from the rear wheel. The vibration also makes a squeaking sound, which occurs once each time the rear wheel makes one full rotation. When I speed up the vibration goes away but I still feel some resistance in the rear wheel. Moreover, when I engage the rear break the vibration comes back very strongly.
I went to a bike mechanic when the issue first arose and he told me this was a problem with the bearings in the rear wheel and recommended that I replace the entire rear wheel as he didn't have any spare parts to fix the bearings with due to the coronavirus supply shortage. I went to a different bike shop and they managed to fix the problem. Everything was fine until today when the problem came back.
Does this really sound like a problem with the bearings in the rear wheel? If so, what is wrong with the bearings to produce this vibration and what is the cheapest way to fix this problem permanently?