For the ring of spell storing, I know a stored spell's save DC/attack bonus is based on the caster who originally stored the spell in the ring.

But say the original caster uses temporary items to boost their spell save DC/spell attack bonus (such as a bloodwell vial) after they've stored a spell in the ring. If the stored spell is then cast from the ring of spell storing, which version of the original caster's spell save DC/attack bonus is used?

• Is it the spell DC/attack bonus of the caster at the time the spell was stored?
• Or is it the caster's current spell DC/attack bonus (i.e. at the time the stored spell is cast from the ring)?

Another situation: Say I cast a spell into the ring of spell storing. I then level up and my proficiency bonus increases. If the stored spell is then cast from the ring, does it use the spell save DC/attack bonus from before I level up (i.e. when it was stored in the ring), or the values after I level up?