It does, because your wifi antenna can resolve greater speeds than your 5g antenna.
My biggest guess is that you are major carrier like att, tmobile and those are greedy as hell - you have 5G data plan for your phone use but your hotspot might be capped at 4G.
How i know? I was running tmobile, those scumbags gave me 3G hotspot on my 5G internet plan - so my 13 mini was freaking fast when using phone internet, but i was nowhere near to do my job remotely on my laptop cause hotspotting was capped at 3G.