Not normal at all. How many coats are down now? What did they use brand and type wise?

Looks like they are pouring from a dirty container that has dried up polyurethane in it. Flakes of polyurethane mixing in with the liquid. Then transfered onto the floor while coating. You can scrape down just the poly and touch it up. If, you cut through to the stain, you're screwed.

This is the 3rd coat because 2nd coat (only planned for 2) had visible brush marks.

These holograms are actually raised areas - where pools of the poly collected due to maybe floor not being perfectly levels? And are basically everywhere across the wood floor.

Is there any way to easily repair this? I was thinking some very fine polish or extremely high grit sanding? You can feel the actual thickness difference when you run your finger against it, so I felt the visible hologram was due to the thickness.

Let me repeat, scrape it down and touch it up. Use a sharp razor. Do not take it to bare wood. Do not sand! These are flakes of polyurethane in the finish. The flooring contractor have been using a dirty container to store their finish.

Follow the recoat specifications and time frames of the product.

This appears to a small puddle caused by stopping the applicator, then not evening it out. Is it normal? Sort of. It happens occasionally, since it's applied by imperfect humans. G&S has the right advice, even though I'm not seeing "flakes of polyurethane in the finish". Your finisher can likely scrape these out with a sharp hand scraper, lightly sand, tape off the boards and recoat them. At worst, another full coat might be required.

Issues like this are far more likely when visibility during coating is bad. Spots that are visible when you can walk around on the finished floor might not be visible as the person applying wet finish is backing their way out. One thing that helps immensely is to have a helper while coating, who can cut in the edges and watch for misses and puddles in the finish.

Good luck!

Thanks so much all! Timothy what you describe feels exactly what I think happened (from my limited knowledge). The issues are pooling of poly coat (attached a few pictures of a different area where the same occurs).

Unfortunately across our floor, there are 20-30 different locations (across roughly 2000 sqft) where this issue has occurred. Is that common or is our contractor not applying properly?

Trying to decide whether we call him in to fix it or cut our losses with him and go with another more experienced contractor to fix.

Not normal for a professional. They were angry that they had to come back to fix their previous work so they rushed. Again. It’s on them to fix it. Hopefully you still owe them a lot

" Is that common or is our contractor not applying properly? "

You have been told repeatedly that it is not common or acceptable. Up to you who you trust to fix the issue but remember this guy has not done much to instill confidence. If you allow him the chance insist on a different team.