Can you please clearly cite what in that briefing makes you conclude this?
Restrictions are discussed in section 4, page 25.
Their recommendations are in part 5, page 31:
"any restrictions on encryption must be contained in laws that are precise and transparent, must be used only when necessary to achieve a legitimate aim and must not discriminate against specific individuals or groups. Critically, any measure interfering with encryption must be proportionate to achieving the legitimate aim for which it is imposed, and the benefits gained through the adoption of such measure must not be outweighed by the harm caused, including to individuals and network infrastructure and security."
The use of 'any' does not imply recommendation. I guess you could interpret the 'only when necessary' part as maybe opening the door to restrictions on encryption, but I feel Amnesty International's wording here intentionally wants us to really consider the drawbacks.
"any restrictions on encryption must be contained in laws that are precise and transparent"
^ This suggests that they think restrictions are possible, whereas many pro-encryption people think that restrictions are mathematically impossible and are stupid to even suggest.
"must be used only when necessary to achieve a legitimate aim"
^ Again, while there is no specific recommendation, they are implicitly suggesting that restrictions are acceptable under certain conditions.
"any measure interfering with encryption must be proportionate to achieving the legitimate aim for which it is imposed, and the benefits gained through the adoption of such measure must not be outweighed by the harm caused, including to individuals and network infrastructure and security."
^ Same thing. In three separate places, they suggest that restrictions are permissible, and they are making recommendations for when they may be permissible.