Time Stop indicates that the caster has 1d4+1 rounds to do whatever they want and that time does not pass for other creatures. Presumably everyone is effectively barred from using their Reactions, but this is not expressly stated. Furthermore, it suggests that the caster could simply walk away from a character they are engaged in melee without using the Disengage action, but that is also not expressly stated by the spell.
Other spells and effects that remove Reactions specifically state as such. Such as Shocking Grasp:
On a hit, the target takes 1d8 lightning damage, and it can’t take reactions until the start of its next turn.
...Monk's Open Hand Technique:
It can't take reactions until the end of your next turn.
...or the Gibbering Mouther's Gibbering ability:
On a failure, the creature can’t take reactions until the start of its next turn and rolls a d8 to determine what it does during its turn.
The exclusion of similar language within Time Stop is notable, so can the caster of Time Stop trigger Opportunity Attacks during the course of their Actions that others character may use Reactions to capitalize upon?
