The computer chip shortage is clearly covid related since more people being at home for school/work meant higher chip demand for various electronic devices. Car companies have had trouble competing for their chip requirements since there are a finite number of chip manufacturers. Supply issues remain with many other companies (absenteeism, labor shortages, transportation, etc.) and the ports where large cargo ships dock have impacted the availability of many items, including components used to make cars. It will likely take many months or perhaps into next year before all of that is behind us.
Rental car companies all compete with each other for the same renters, so prices will likely go down, even if slowly as things stabilize. If one rental company tries to keep their prices high, they will just lose business to some other brand who is able to lower their prices.