Mods: cealus-forge-3.2.0+1.20.1.jar curios-forge.5.9.0+1.20.1.jar EnigmaticLegacy-2.29.0.jar Patchouli-1.20.1-84-FORGE.jar
Recreation:

1. Create new world (creative, cheats on, peaceful)
2. Equip cursed ring, scroll of a thousand curses, enchanters pearl
3. rejoin
   then the scroll and pearl should be in your hotbar again

Together with those, Emblem of Bloodstained Valor unequips as well, on Forge 1.18.2 40.2.21, Enigmatic Legacy 1.18.2, 2.25.0, Curios 5.0.9.2, Caelus 3.0.0.2.

Also experiencing this in 1.20.1

Experiencing this with Pact of Infinite Avarice scroll, on a server running Cisco's Fantasy Modpack v4d, mc 1.19.2, Forge 43.3.5, Enigmatic Legacy 2.26.5. Item returns to inventory on relog, or drops on ground if inventory is full.

yep, expiriencing the same in 1.20.1, now Testament of Contempt included