After Steven Moffatt renewed the Regeneration cycle in his 50th Anniversary specials it was left unclear whether it was another 12 regeneration cycle or an infinite one - in 'Kill the Moon' we see it stated very clearly that the Doctor isn't sure whether he now has limitless Regenerations, meaning neither did Moffatt know for sure either. So when you think on that you have another example of how Moffatt had been gradually undermining the old rules the character and the series lived by and we arrived at the point where there were no rules... no rules on time-travel, no rules on what the Tardis could and couldn't do, no rules on regeneration energy, no rules on how many regenerations were possible, no rules on death even.
At this stage, with this Timeless Child reveal, the process is finally complete. Anything Goes. Absolutely Anything....
Should have no regens limitations, heck, still even sure why has to change as should be fully immortal