I have a tex file
\documentclass{amsart}\usepackage{amsthm,amssymb,zref-clever,mathtools}\zcsetup{cap=true,comp=false,sort=false}\zcRefTypeSetup{equation}{ Name-sg=, name-sg=,}\mathtoolsset{showonlyrefs}\usepackage[hypertexnames=false]{hyperref}\hypersetup{ colorlinks=true, linkcolor=blue,}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\newcommand{\addtheorem}[1]{% \AddToHook{env/#1/begin}{% \zcsetup{countertype={theorem=#1}}% }% \zcRefTypeSetup{#1}{Name-sg={\MakeUppercase #1}}% \newtheorem{#1}[theorem]{\MakeUppercase #1}%}\numberwithin{equation}{section}\newtheorem{theorem}{Theorem}[section]\addtheorem{corollary}\addtheorem{proposition}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\makeatletter\ExplSyntaxOn\int_new:N \g__example_position_int\prop_const_from_keyval:Nn \c__example_envs_prop { myalign = align, myaligned = aligned, myalign* = align*, myaligned* = aligned*,}% Define the custom align command\cs_new_protected:Nn \__example_align: { \int_gincr:N \g__example_position_int \c_alignment_token \bool_if:nT { \prop_if_in_p:NV \c__example_envs_prop \@currenvir && \int_compare_p:n { \g__example_position_int > 1 } } { \quad }}% Make & active globally or in a group\char_set_catcode_active:N \&\char_set_active_eq:NN \& \__example_align:\prop_map_inline:Nn \c__example_envs_prop { \NewEnvironmentCopy { #1 } { #2 } \hook_gput_code:nnn { env / #1 / begin } { . } { \int_gzero:N \g__example_position_int }}\hook_gput_code:nnn { cmd / measure@ / after } { . } { \int_gzero:N \g__example_position_int}\ExplSyntaxOff\makeatother\begin{document}\section{Intro}\begin{proposition}We have\begin{myalign} & a \\& = \begin{myaligned}[t] \label{eq1}& b \\& + c.\end{myaligned}\end{myalign}and\begin{myalign} & a \\& = \begin{myaligned}[t] \label{eq2}& b \\& + c.\end{myaligned}\end{myalign}\end{proposition}We have \zcref{eq1} and \eqref{eq2}.\end{document}
Above, myalign and myaligned are modified versions of align, aligned and taken from this answer.
Could you explain why \zcref{eq1} wrongly gives Proposition 1.1. On the other hand, \eqref{eq2} works fine.