Little brown bumps

Definitely scale. The size variation is probably just different age classes. You want to control these NOW or they will multiply very fast.

You said you have a "couple" of orchids. If you truly have 2 plants then an appropriate control method could be a soft brush (old toothbrush, etc) and isopropyl alcohol (70%). Make sure it is isopropyl alcohol. Dip the brush in alcohol and gently brush the areas where you see the scale. Then take a paper towel or soft cloth and wipe the scrubbed area clean. Once you have treated the visible scale take a clean paper towel soaked in the alcohol and wipe the entire plant to remove eggs and other insects that you may not be able to see.

Repeat this process weekly for 3 weeks.

Basically you need to get rid of the adults and as many eggs as possible with the first treatment. Subsequent treatments are to remove insects that have hatched from eggs that were missed on the previous treatment. The brown bumps are the female insects but the males will be masses of tiny white capsules side-by-side as well as end-to-end packed very tightly. You may see both on your plants.

Be sure to look under the brown papery sheaths at the base of the pseudobulbs and in any tight hidden nooks. Cotton swabs work well for those tight spots.

If you had more plants then a systemic insecticide might be necessary but with just a few this should work for you. Oh, wipe all of the other plants with alcohol even if you can't see the scale yet. They are probably infected. Inspect them regularly, too.

Good luck and welcome to the forum.