I have the same issue. Indexing is extremely slow and yet fully loads a whole core, even while I'm actively working, of my 4-core Surface Book 3 13,5" (which has no active cooling which makes this constant high CPU load even worse as it leads to throttling).
Try using Teams and Miro while indexing already takes a whole core away from you - the device becomes completely unusable. Indexing speed is about 5 files/minute and I'll have about 250.000 items to index (amount of indexed items before I did a index reset to see if that helps - it did not).
I'll try the resolutions mentioned here like refreshing the installation. Yet, this is something MS should urgently fix. It's not that this is the only Windows process that seems to escalate on CPU usage frequently, it's just by far the worst one. Makes Windows unusable on low-wattage CPUs and fanless systems. Those M1 Macs are becoming really attractive to me ...