For smartphones, (EU) 2023/1670 Ecodesign Regulation (lex specialis) overrides the general Batteries Regulation. The glued (non-user-replaceable) battery is allowed only for professional repairers if all these are met:
Battery endurance:
≥ 83% capacity after 500 full charge cycles
≥ 80% capacity after 1,000 full charge cycles
Water/dust protection: Device must achieve at least IP67 rating.
Spare parts & repair info:
Battery (and back cover if needed for replacement) available to professional repairers for 7 years after end of sales.
Repair manuals, diagrams, and tools provided to professionals.
If these conditions are fulfilled, it can stay glued