Intel is supply constrained and has been for some time. Apple not buying Intel CPUs doesn't cost them anything because they will still have full fabs and still sell everything they can make.Well macs are 10% of the computer market so even if apple isn't a threat to x86 thats still a sizeable chunk of money not going into intel anymore.
At most since Apple has always chosen more costly SKUs (because they wanted the lowest power CPUs possible) it costs Intel a bit if the orders that replace Apple's are at a lower ASP. On the other hand Apple was a pretty demanding customer, and Intel spent millions of dollars meeting their demands for special SKUs, special packaging, etc. which they won't have to deal with anymore.
If there was ever a time for Apple to drop Intel without Intel feeling any pain, this is the time. Not only was Intel supply constrained due to their self-inflicted wounds delaying process transitions before coronavirus hit, WFH and remote schooling spiked PC demand up for the first time since the market went into decline a decade ago. Intel's traditional PC customers no doubt have enjoyed Apple moving the bulk of their Mac sales (volume wise at least) to ARM already and freeing up Intel's capacity for their needs.