printf fails in version 5.2.026-3

[szigetva]

Configuration Information [Automatically generated, do not change]:
Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS: -march=x86-64 -mtune=generic -O2 -pipe -fno-plt 
-fexceptions         -Wp,-D_FORTIFY_SOURCE=2 -Wformat -Werror=format-security   
      -fstack-clash-protection -fcf-protection -g 
-ffile-prefix-map=/build/bash/src=/usr/src/debug/bash -flto=auto 
-DDEFAULT_PATH_VALUE='/usr/local/sbin:/usr/local/bin:/usr/bin' 
-DSTANDARD_UTILS_PATH='/usr/bin' -DSYS_BASHRC='/etc/bash.bashrc' 
-DSYS_BASH_LOGOUT='/etc/bash.bash_logout' -DNON_INTERACTIVE_LOGIN_SHELLS
uname output: Linux delg0 6.6.36-1-lts #1 SMP PREEMPT_DYNAMIC Thu, 27 Jun 2024 
12:26:27 +0000 x86_64 GNU/Linux
Machine Type: x86_64-pc-linux-gnu

Bash Version: 5.2
Patch Level: 26
Release Status: release

Description:
        printf works in version 5.2.026-2, fails in version 5.2.026-3

Repeat-By:
        contents of tmp.sh begins --------
        #!/usr/bin/env bash
        a=1
        printf "%.2f\n" "$a"
        contents of tmp.sh ends ----------

        5.2.026-2> ./tmp.sh
        1.00

        5.2.026-3> ./tmp.hs
        nan

Fix:
        I don't understand what is happening, my current fix is downgrading to 
5.2.026-2.