Suppose a druid is in possession of a sentient magical item that possesses telepathy. If the druid wild shapes and chooses to merge the item into their form, will the item's telepathy be suppressed? The rules say, "Equipment that merges with the form has no effect until you leave the form." Is telepathy an "effect"?
Unless someone is aware of any Sage Advice to the contrary, there doesn't actually appear to be a definitive official ruling on how sentient items behave with merge effects like that. The two closest options to rules as written would be to either have the sentient item merge with the player and have all of its properties (including its sentience) suppressed for the duration, or to rule that the item is not equipment, but an NPC (as stated on page 214 of the DMG), and therefor can't merge with the character as part of this effect. Obviously other options are available at the GM's discretion.