Hot water to bathroom sink slows to a trickle after shutting off valve for a moment
It sounds like some debris from the shutoff valve ended up in the faucet cartridge or the airator. The flow starting strong and quickly could even be a chunk of the shutoff valve seat that has crumbled getting stuck so the flow starts out good then the chunk blocks the flow to a trickle, disassemble and possibly flow water into a bucket will probably flush the debris out of the system.